Indiana State Treasurer Richard Mourdock (R) raised more than $300,000 in the last three months for his campaign to defeat Sen. Dick Lugar (R-Ind.), enough money to allow the Tea Party candidate to compete against the longtime senator. But Lugar outraised Mourdock by a 3-to-1 margin, bringing in $900,000. Lugar has $3.5 million cash on hand, according to his campaign. Mourdock's campaign has not yet released its cash-on-hand total.

Mourdock's haul, provided by his campaign, is a solid but not overwhelming total for an outsider looking to knock off an entrenched incumbent. By comparison, Sen. Marco Rubio (R-Fla.) raised a slightly higher amount, $350,000, during the same period in 2009. Rubio wound up forcing incumbent Gov. Charlie Crist, who had been the odds-on favorite in the primary, to leave the GOP before beating him and Democrat Kendrick Meek by a gaping margin in the general election.

Other Tea Party candidates who knocked off incumbents or establishment choices in 2010, such as Sen. Mike Lee (R-Utah), Ken Buck in Colorado and Christine O'Donnell in Delaware, had not even started fundraising at this point in 2009.

Lugar, the most senior Republican in the Senate, has not had to run a real campaign in decades. He did not face major-party opposition in 2006, and the last time he was held to under 60 percent of the vote was in 1982. His respectable but not overwhelming total, combined with Mourdock's solid performance, indicate that this could be a tough race.