Steve Hilton arrives on Downing Street on Nov. 1, 2010, in London. The former aide to British Prime Minister David Cameron has launched Crowdpac, a fundraising and ratings site for American politicians. (Oli Scarff/Getty Images)

Dressed in a striped T-shirt and shorts, Steve Hilton is enthusiastically gesticulating at his MacBook Air, explaining how he intends to reshape American politics with a Web site. This week, he launched Crowdpac, a political start-up that helps ordinary voters to find and donate to candidates who fit with their own views — a for politicians.

After bold, unconventional attempts to disrupt British politics, the colorful former aide to Prime Minister David Cameron is turning his attention to Washington. Having worked in politics for two decades, advising the Conservative Party with a radical zeal, the man dubbed by the British press a “pint-sized Rasputin” is aiming high with his new venture.

Powered by a humongous amount of data, custom algorithms and a few political brains from Stanford University, he hopes Crowdpac will further his long-term goal of empowering individuals to make their own decisions about politics without the filter of lobbyists, political insiders and big donors. Whether he will have more success with this venture than similarly ambitious enterprises that fell short in Britain remains to be seen.

“I think the truth is it goes right back to my inspiration for getting involved in politics generally,” he says. “Thinking back to my time in the U.K., before the election and then working in the British government, the thing that has really driven me is this idea of giving power to people and taking power out of the hands of those who try and grab it all for themselves.”

On Crowdpac, every congressional candidate — Hilton hopes to expand the site to more political races in the future — gets scored on a continuum between conservative and liberal and a scale of 0 to 10. For example, Sen. Rand Paul (R-Ky.) has an overall score of 9.1 conservative. In most categories, Crowdpac rates him as 10 conservative, but in the intelligence-and-surveillance category, he’s a 10 liberal.

The Crowdpac score is calculated from a mixture of how candidates have voted, who they’ve donated to, who has donated to them and what they’ve said. The site has compiled over a million words, 15,000 contributions and 3,100 votes for Sen. Mark Udall (D-Colo.), for example. The patent-pending algorithm then sifts through the data and generates a rating.

“What we’re really trying to do is help people make a judgment about their candidates using objective information,” Hilton says. “I think what people are really crying out for is simple information they can trust when they’re bombarded by attack ads, fundraising pitchers and all sort of comment and opinion all over the place increasingly.”

Crowdpac’s ability to narrow down particular individuals with its variety of filters — on location, party preference and how strongly you feel about 15 key issues — is not dissimilar to a dating Web site. Hilton laughs at the comparison, saying it is not the first time he’s heard it.

“It is what we’re trying to do,” he says. “We’re trying to make politics something that everyone can get involved in and participate in in a simple way.”

Crowdpac also intends to create a series of lists to help voters navigate the world of politics. For example, the names of the most rebellious members of Congress, the most hard-line conservatives and the most loyal party members are all available on the site. Eventually, members of the public will be able to mine information and create BuzzFeed-style lists for themselves.

As with any data-driven site, the usefulness of Crowdpac will be dictated by the quality of the data, since it is based on the assumption that voters have the energy and interest to dig into the information it offers. And candidates, particularly congressional ones, may challenge their scores if they believe them to be inaccurate.

Shelia Krumholz, the executive director of the Center for Responsive Politics, has used Crowdpac, and although it is in its early days, she welcomes the site as a way to help people better understand politics.

“It seems to build on work from other watchdogs, including our, but with some streamlined views of issues and ideologies,” Krumholz says. “It will be a while before we can see whether Crowdpac can do everything they say it can.”

“But we need bright minds with expertise in this field to make politics as accessible as possible,” she says. “Breaking down barriers can only be a good thing.”

From Downing Street to Silicon Valley

The United Kingdom has been the recipient of many political advisers from Washington — former Obama strategists David Axelrod and Jim Messina are both working for political parties in Britain — but it’s rare for an adviser from London to come here.

Although Hilton has lived in California for several years, he remains mostly unknown in Washington political circles. Across the pond, Hilton has gained notoriety for his big ideas, casual fashion sense and secretive manner. He avoids the press and hasn’t given interviews until now.

Whereas backroom advisers tend to be slick professional operators in suits, Hilton is anything but. His career began at the advertising agency Saatchi & Saatchi in the early 1990s, where he worked on the Conservative Party’s successful 1992 general election campaign with a young Cameron. After becoming disillusioned with the direction of the party, he founded a consulting firm, Good Business, to advise clients such as McDonald’s and Coca-Cola on being socially responsible.

Hilton returned to the Conservative fold in 2005 when Cameron was elected leader of the party. He became indispensable to Cameron, both in opposition and in government — so much so that he became known as “Dave’s brain.”

Working closely with the party leadership, Hilton talked of “smashing up the machine” and slashing $40 billion from the welfare bill. Hilton bounced around 10 Downing St. in socks and shorts with a T-shirt emblazoned with the motto “Pillage before plunder — what a blunder” and “Plunder before pillage — mission fulfillage.”

He was a key proponent of the government’s efforts to bring technology start-ups to the Old Street neighborhood of London, branded Silicon Roundabout. Throughout his time in government, Hilton worked to create more of an entrepreneurial culture in Britain.

Such is Hilton’s influence on British politics that a fictional TV character is said to have been inspired by him. There are parallels between Hilton and Stewart Pearson, a follically challenged, un­or­tho­dox communications director played by Vincent Franklin on the BBC’s political satire “The Thick of It,” a sister show to HBO’s “Veep.” Both are on a mission to spruce up their parties’ image, both are fans of technology, and both think the unthinkable.

Hilton’s ideas to reshape who controls politics are not new. While in government, he pushed for freeing up data, more transparency and accountability in all branches of government, empowering local communities and giving businesses more freedom.

His magnum opus was “the Big Society” — a political ideology that united Hilton’s most radical ideas. The concept formed a cornerstone of the Conservative Party’s 2010 election manifesto, but the government was never able to adequately explain to the electorate what it was.

After just two years at Downing Street, Hilton’s career in the corridors of power came to an end. He quit in 2012 after becoming disillusioned with Cameron’s progress and the lack of boldness and took a sabbatical at Stanford University.

Looking ahead to 2016

From his time in the United States, Hilton has discovered there are similar problems in both nations, notably the apathy and disillusionment that is causing headaches for Obama and Cameron.

“In both countries, you do have a sense that people are really feeling that their political system doesn’t properly represent them,” he says. “There is this sense they want to have more control and more power. There’s a sense of frustration that is something very common.”

There are obviously some differences — the importance and impact of money for one — but Hilton sees change on the horizon in Britain and the United States.

“People are really looking for greater sense of control of what happens in their lives, about the issues they really care about, and they feel that the political system doesn’t necessarily deliver,” he says.

Crowdpac is a for-profit venture, although there are no fully formed plans yet as to how the site will make money. One idea under discussion is to take a percentage of donations made to candidates through Crowdpac. As the project develops, Hilton says “we’ll also be testing different approaches to generating revenue.”

The company has hired two of Washington’s heaviest-hitting lawyers in the realm of campaign finance: Benjamin Ginsberg and Marc Elias. Crowdpac told the Federal Election Commission it expects to deduct about 8 percent of contributions, which will be split with its processing firm.

The timing of the site’s launch is clearly targeted toward the midterm elections in November. The team hopes this election cycle will be a launching pad for future versions, particularly ahead of the 2016 election.

“We wanted to really test our service with people in the context of a real election campaign,” Hilton says. “We’ll learn a lot from it, we’ll learn what people find most useful and most interesting and then build on that with the next version of Crowdpac.”

The team behind the site consists of three co-founders, half a dozen staff members — made up of political scientists and data engineers — and a similar number of freelance contractors. By picking knowledge and skills from California, has Hilton given up entirely on British politics? His last appearance was in September 2013, when it was reported he was assisting the prime minister in speechwriting again.

“We moved to America with our family a couple of years ago, so this is where we live, this our home, and that’s really the answer,” he says.

When Crowdpac is fully launched, might Hilton be tempted back to Britain to help out his old friend Cameron with the 2015 general election? Hilton dodges the question.

“Crowdpac is what I’m passionate about,” he says. “I want to see it develop and grow, and I’m not really thinking anything except a long-term future for this business — but more importantly, for what this business can do for the long-term future of America.”

Matea Gold contributed to this report.