Political novice and Tea Party insurgent Rand Paul is poised to upset "establishment candidate" Trey Grayson in the Republican primary to replace Sen. Jim Bunning (R-KY) next Tuesday. Grayson, Kentucky's secretary of state, was recruited by Senate Minority Leader Mitch McConnell (R-KY), and was the presumptive GOP nominee until Paul's grassroots candidacy took off. (Watch Rand Paul warn a "Tea Party tidal wave is coming")

Who is Rand Paul?
Randall Paul, 47, is an ophthalmologist and anti-tax activist who's never held elective office. He started the group Kentucky Taxpayers United and is, famously, the son of Rep. Ron Paul (R-TX), the libertarian presidential candidate. Rand Paul lives in Bowling Green, KY; he is married, and has three children.

What is his platform
Newsweek's Howard Fineman describes Paul as "a 100-proof libertarian." He wants a balanced federal budget, Congressional term limits, and an end to all government bailouts, earmarks, and the "socialist" health care law. He also favors pulling out all U.S. military forces from missions abroad, shuttering the Department of Education, and legalizing medical marijuana.

Who's endorsing Paul?
Notable backers include Bunning, Sarah Palin, Sen. Jim DeMint (R-SC), and James Dobson of Focus on the Family, who switched over after initially supporting Grayson. Paul was also endorsed by the Lexington Herald-Leader, who said that while his "obviously sincere" but "untested" ideas could "marginalize hims as a gadfly" in the Senate, he is the best choice to steer the GOP from the "Bush-Cheney-McConnell path."

Who's endorsing his opponent?
Grayson's most prominent backer is McConnell, but he's also been endorsed by ex-Vice President Dick Cheney, Rudy Giuliani, locally popular U.S. Rep. Hal Rogers (R-KY), and the U.S. Chamber of Commerce.

What do the polls say?
Most major polls give Paul a double-digit lead, about 15 points on average. But 20 percent of Republican voters are still undecided, and Grayson has a financial advantage: $820,374 in cash on hand at the end of April plus another $66,700 in the first week or May; Paul had $169,000 in April, plus $15,400 in the first week of May.

So why is the GOP establishment leery of Paul?
A Paul victory would be the third big win in a row for the Tea Party wing of the GOP, after Sen. Robert Bennett's primary defeat in Utah and Gov. Charlie Crist's rejection by Republicans in Florida. But it would also be an embarrassing blow to McConnell — Paul has said he may not support McConnell's bid to stay on as the Senate's top Republican.

Can Paul win in November?
Kentucky is becoming redder every year, says Fineman, so "I wouldn't bet against Paul." Others are more skeptical. Between his fringy "Paulite" views on returning to a "gold standard utopia," his flirtation with 9/11 conspiracy mongers, and his nonchalance about the threat of Iranian nukes, says David Frum in The Week, "Rand Paul is a walking target for Democratic negative ads in a closely divided state."

Sources: AP, The Atlantic, The Week, Newsweek, Lexington Herald-Leader, National Journal, Rand Paul's campaign site, MarketWatch, Washington Post