It's going to be a nail-biting finish. The battle between David Cameron and Ed Miliband to be the UK's next prime minister has become the country's closest and most unpredictable election race in years.
Neither are expected to win enough seats to grant them an overall majority, with polls showing them roughly neck and neck throughout the campaign so far.
But it is not just the leaders of the Conservative and Labour parties who are facing off against each other in this election.
Behind this battle of personalities and ideologies lies another contest that perhaps tells us even more about UK politics than seeing the age-old Labour/Tory war play out one more time.
Two of the US's most renowned political strategists, David Axelrod and Jim Messina, who worked side by side on Barack Obama's 2008 and 2012 successful presidential bids, have been shaping this year's UK election campaigns — on opposing camps.
Jim Messina, chief of staff during Obama's 2008 election bid and his campaign manager in 2012, was hired by the Conservative Party in August 2013.
Eight months later the Labour Party announced the man behind Obama's infamous "Yes We Can" slogan, David Axelrod — who has known the president since 1992 and first worked for him during his Senate bid in 2004 — would be working as a senior adviser to Labour's campaign.
Axelrod and Messina were once close colleagues who fell out during Obama's 2012 campaign, when Messina is said to have pushed Axelrod out of the inner circle, despite the latter officially being in charge.
In the US, their British clash has been framed as a mutual attempt to settle the score. The UK election is shaping into "a proxy competition between two titans of the "No Drama Obama" campaigns who are acting out their ideological and personal conflicts on a faraway stage," said The New York Times last May.
Messina was accused of being a hypocritical mercenary by some commentators for taking a job with a with a party whose ideology is very different to what Obama represents — though conservatism in the US and the UK are two very different beasts.
More importantly for the UK, the two men's key positions in the upcoming election has turned the "American invasion of British politics… [into] a full-on assault," according to The Washington Post.
The fact that Obama's top campaign gurus are now playing key roles on both sides of the election is sign of just how embedded the American influence on UK politics has become.
From glitzy choreographed manifesto launches to television debates, soundbites and highly sophisticated use of social media, UK elections are now more American than ever before, analysts agree. What this means for British politics, however, is still up for debate.
The history of US strategists and campaign techniques in the UK goes back a long way, Dr Margaret Scammell told VICE News, adding that it was easy to see why.
"The US has a colossal number of voters and a well-developed industry of professional political consultants," said Scammell, a political scientist at the London School of Economics who specializes in campaigning and the Americanization of global politics. "So they have tremendous amount of expertise and experience, coupled with a huge amount of money and cutting edge technology. This has made the US the world's laboratory for campaigning techniques."
She pointed to former Conservative prime minister Margaret Thatcher's use of pollsters who had worked for Republican president Ronald Reagan as one of the earliest examples of US strategists landing on British shores.
In the 1997 election, Stan Greenberg, who had played a leading role in the elections of Bill Clinton and Nelson Mandela, became the first major US strategist to take a senior role with a UK politician, working as campaign adviser to Tony Blair. Bob Shrum, Joel Benenson and Pete Brodnitz have been among those who followed — all well-known Democrat pollsters who were contracted by the Labour Party.
More important than the strategists themselves were the US campaign techniques that have been adopted, said Scammell, which the UK parties would have copied from across the Atlantic regardless of who they employed.
The most significant over the decades has been the sophisticated use of data, gathering not just numbers on voters but information on how they think and feel — known as "voter modeling."
"In the mid-Noughties the Republicans gave the Conservatives their "Voter Vault" software — software which allowed them to collect and organize huge amounts of voter data, with records of canvas returns and postcodes," said Scammell. "You can use that to identify people who may be amenable to your message."
Pete Brodnitz, a US consultant who worked for Gordon Brown in the 2010 election, helped develop even more sophisticated voter modeling techniques in a Virginia gobernatorial election in 2005. "I was able to add information on how voters would come down on specific issues into the modeling," Brodnitz told VICE News. "And modeling has got more and more advanced every year since then. Obama took everything to a new level."
The voter data is then used for "microtargeting" — giving individual or subgroups of voters tailored campaign messages, which can change day to day or even hour to hour, responding to events as the data is constantly refreshed.
Obama's 2012 campaign was the most technologically advanced in history, spearheaded by Messina who is one of the world's leading experts in data campaign strategy, and is reportedly now focusing on this technique for the Conservative Party.
Much stricter privacy laws and restrictions on campaign spending mean UK parties cannot gather data and microtarget voters to the extent that their US counterparts do, Brodnitz pointed out. But they are able to harness the techniques using social media.
Using demographics collected by Google, the Conservatives are using YouTube to show certain adverts to specific viewers in different constituencies, reported Buzzfeed in February, as well as spending 100,000 a month just on Facebook adverts. Political advertising is banned on UK television, apart from the set party political broadcasts, but there are no laws restricting online videos.
A Conservative Party source told The Daily Mail last month that their online presence reached three million people a week, and videos tailored to specific voters' interests were going viral.
"This is the first year we've seen these modern US microtargeting techniques burst onto the UK scene," Iain Anderson, chairman of the UK-based Association of Political Consultants, told VICE News. "Social media campaigns are being deployed and people's inboxes being bombarded, especially in marginal constituencies."
The content of many of the YouTube ads marks another example of a classic American technique — they garishly attack the opposition for chaotic policies and incompetent leadership, to a level not seen before in British elections. The ads use creepy sound and visuals to show Miliband entering Downing Street with Sinn Fein leader Gerry Adams and the Scottish National Party's Alex Salmond, or failing to remember Britain's deficit during a taxing game of Scrabble, among other nightmare scenarios.
Attack ads have long been an American staple, first used to major effect by George HW Bush. US advertising agency Saatchi & Saatchi created the first such ads for a British politician during Thatcher's campaign in 1979 and 1992, used on billboards and in party political broadcasts. One of most famous, showing a dole queue snaking into the distance with the headline "Labour's Not Working," created so much coverage and controversy that it spurred Labour into delaying the 1979 election, which in turn led to them losing, some believe.
The Conservative Party has consistently used negative advertising at a far higher rate than Labour (between 80 and 90 percent of their ads have been negative, compared to around 40 percent of Labour's, Scammell's research has found).
"It's believed that negative campaigning resonates more with voters, is more memorable," said Scammell. "But it can backfire and boomerang back on you, as people often don't like it."
Another major evolution of UK campaigning into an American style can be seen in the now standard carefully-choreographed imagery and soundbites, typically focused around the party leader rather than the party itself.
Thatcher was again the first British politician to try this, adopting Reagan's "power visuals" in the 1983 election to create a campaign based around a series of images.
"Reagan strongly believed that voters were more influenced by the images they saw than the words they heard," said Scammell. "Thatcher took that on, organizing tours to coincide with television news schedules. The term 'photo opportunity,' hardly used before, became known."
Thatcher's campaign team dedicated their efforts entirely to television coverage, touring the country in a battle bus, inviting cameras into Downing Street and holding rallies similar to presidential conventions. She won the most decisive victory in modern British history.
Tony Blair's 1997 campaign took the use of imagery to a new level with the creation of New Labour as part of "Cool Britannia", and shiny manifesto launches and televised leaders' debates are now a regular feature of UK electioneering. Whereas different party members used to present different policies during campaigns, now the party leader is almost always the major focus of the national campaign. "As we moved to focus on visuals, the personality [of the leader] became fantastically important," said Scammell.
Axelrod is known as the mastermind of creating winning personas for candidates that embody the message of their party, skills which could prove crucial in transforming the image of Miliband from a woolly, geeky underdog into a strong and capable leader dedicated to tackling inequality.
Soundbites are a crucial part of this, perfectly illustrated by Miliband's performance in the leaders' debates with television presenter Jeremy Paxman, where the line "Hell yes I'm tough enough [to be prime minister]" became the standout moment of the night. "That was a pretty Americanized line," said Anderson. Miliband enjoyed a bounce in the polls following the broadcast, though more voters still believed Cameron would make a better PM.
It is easy to imagine that all this focus on image and data means politics has become more superficial and sneaky — especially given the use of professional consultants who can work together for one party in the United States then end up on two sides with opposing ideologies in Britain.
But as a general rule, consultants really do believe in the message they are selling, said Brodnitz. It's not about helping the candidate play mind-games but about helping them communicate their values to voters in the most effective way possible.
"I've turned down work when I strongly disagreed with the client's politics," he said. "When you start to work for someone you really start to see things from their perspective and get very emotionally committed. You don't want to find yourself saying to people a few years later, "Oh they were just misunderstood," about someone whose politics you did originally not believe in."
Messina working for the Conservative Party was very different to him working for the Republicans, said Brodnitz, as the Tories' issue positions were much closer to the center, though he acknowledged that Axelrod and Messina were "both professionals onto their next engagement now the Obama effort is over."
Scammell acknowledged that many people do believe the Americanization, of professionalization of campaigning, "has done a huge disservice to democracy." But she disagrees. "We do need campaigns to motivate people, and you could use these techniques to run terrific campaigns. The idea that political consultancy is all peopled by unscrupulous tricksters looking to hoodwink the public is quite wrong. There are fundamental problems with politics, but they are not problems with the campaigning, they are with the system itself."
Follow Miriam Wells on Twitter: @missmbc