(CBS News) In a year that has Democrats playing defense in the Senate, Tuesday night's Republican Senate primary in Indiana has given Democrats an opening they weren't expecting.
Democrats say Indiana Treasurer Richard Mourdock's victory over longtime incumbent Sen. Richard Lugar puts the seat in play -- much in the way Democrats prevailed over Tea Party candidates in 2010, such as Sharron Angle and Christine O'Donnell. The GOP counters that Mourdock isn't some untested fringe candidate, but a solid conservative with strong ties to the state. On top of that, they argue Democrats simply don't have a chance in a red state when this year's election will primarily be about President Obama.
Had Lugar, a the six-term senator, won the primary, it's widely agreed that he almost surely would have won the general election. But with a conservative like Mourdock on the ballot, Democrats think Rep. Joe Donnelly of Indiana's 2nd district has a shot -- he's a moderate who opposes abortion rights and supports gun rights and who managed to survive the Tea Party's attacks in his 2010 House race. And Democrats are ready for a fight.
"Last night's results not only make Indiana a prime pick up opportunity for Democrats but also change the Senate landscape dramatically by adding another state to the map where Democrats are on offense," Shripal Shah, a spokesman for the Democratic Senatorial Campaign Committee (DSCC), told Hotsheet.
Polling bears out the notion that things are looking up for Democrats in the Hoosier state: One Democratic poll conducted in March gave Donnelly a six-point lead over Mourdock (the Democrat would fare much worse against Lugar, the poll shows). An independent poll conducted in March by Howey/ DePauw University showed Donnelly and Mourdock essentially tied in a match-up, while Donnelly would clearly lose to Lugar.
The DSCC Wednesday morning sent an email to supporters calling Mourdock "this year's Sharron Angle - an extreme candidate who questions whether Social Security and Medicare are constitutional and thinks Washington should be even more partisan."
In a separate memo, DSCC executive director Guy Cecil compared Mourdock to another 2010 Tea Party loser, Colorado's Republican Senate candidate Ken Buck. "Like Ken Buck, Richard Mourdock is another right wing extremist who is too far out of the mainstream for independent voters," the memo says.
However, Republicans sound confident that Mourdock can prove he's a serious candidate.
"I knew Sharron Angle and Christine O'Donnell," one Republican strategist, who remained anonymous to speak freely about the race, told Hotsheet. "He's not either of them. He's running as a conservative Republican."
The strategist added that the GOP should be "fully confident" Mourdock can win the general election.
Steve Shine, chairman of the Allen County Republican Party,told the Ft. Wayne Journal Gazette that Mourdock's "grass-roots organization and on-the-ground efforts was one of the best efforts I've ever seen in the state."
Shah of the DSCC countered, "Just because Richard Mourdock hasn't gone on TV yet to declare that he isn't a witch doesn't make him any less extreme than the likes of Christine O'Donnell and Ken Buck."
While Mourdock hasn't made any remarks as risky as, he has a record that Democrats are ready to use against him.
Much in the way Angle said in 2010 that creating jobs is "not my job as a U.S. senator," Democrats point out that Mourdock said, "I didn't take a pledge that I would support every job in Indiana under whatever means it takes to do it."
While Democrats are busy tying Mourdock to the Tea Party, Republicans will be tying Donnelly to Mr. Obama. Mr. Obama won Indiana in 2008, but he's clearly not popular there now -- the Howey/ DePauw University poll conducted in March showed the president losing in a match-up against Mitt Romney, 49 percent to 40 percent.
In an email to voters on Wednesday, Mourdock wrote, "Joe Donnelly has been a loyal soldier for Barack Obama. He was a deciding vote on ObamaCare. He voted for Obama's Stimulus program and his bailouts. Donnelly voted for Obama's policies so often that the President calls him his 'Partner.'"
Rob Jesmer, executive director of the Republican Senatorial Campaign Committee, said on Wednesday that the race is likely to mirror the 2010 Senate race, when Democrat Brad Ellsworth lost by 15 points to Dan Coats.
"This is a Republican state," Jesmer told "Face the Nation" anchor Bob Schieffer on CBSNews.com's weekly web series "Face to Face." "I just don't think that people of Indiana, Hoosiers, are going to support somebody who supported health care, who supported the president's stimulus, supported Nancy Pelosi for speaker. These kinds of things are not going to go well in Indiana, so Richard Mourdock's going to win and we look forward to helping him do that."
The Club for Growth PAC, the political action committee that poured millions into the primary backing Mourdock, is now slamming Donnelly as "in lock-step with Nancy Pelosi and Barack Obama on nearly every issue."
Donnelly, however, is a clear moderate who says he's interested in carrying on Lugar's legacy of bipartisanship. "I hear from everybody, and they say 'Joe, nowhere but in Washington do they think not working together makes sense,'" he told the Washington Post. "We're not hired to fight. My question about everything I do is, does it make our country stronger?''
His moderate positions helped Donnelly withstand more than $2 million in attacks from Republicans and their allies in his 2010 House race, Democrats point out. And now that he is campaigning on a statewide level, Donnelly can benefit from support from the more-liberal 1st congressional district and more liberal constituencies across Indiana.
"Today there are tens of thousands of disillusioned Hoosiers who have supported Dick Lugar their entire voting lives and are likely dismayed by the polarizing, extreme forces that defeated him," Cecil of the DSCC said in his memo. "While Richard Mourdock is poorly positioned to appeal to these voters, Joe Donnelly is exactly the kind of reasonable, honest, job-focused, centrist these voters have always supported."