Mourdock has scrambled to recover since the gaffe, but it has taken a toll in the closing days of a competitive race. The Howey/DePauw University Battleground poll also showed that the tea party-backed state treasurer isn't winning over women, independents and a percentage of Republicans.
Mourdock also has struggled to satisfy backers of six-term Sen. Richard Lugar, the man he defeated handily in the May GOP primary.
"The only poll I'm talking about today is the new unemployment numbers," Mourdock told The Associated Press during a stop at his Indianapolis campaign headquarters on Friday.
The Labor Department reported that 171,000 new jobs were created last month while the unemployment rate ticked up to 7.9 percent.
GOP failure in the Hoosier state, combined with the likely loss of seats in Maine and quite possibly Massachusetts, would put Republicans in a deep hole — down seven seats to a majority if President Barack Obama wins a second term, needing six if Romney prevails.
Facing that reality, the GOP would have to win all the competitive open seats now in Democratic hands — Nebraska, North Dakota, Virginia and Wisconsin — plus knock off incumbents in Montana, Ohio and perhaps Pennsylvania to assume control.
In cards, football and politics, it's called running the table and it's a tall order. Democratic currently have the Senate edge, 53-47.
"We're very hopeful about Indiana and other opportunities to win other Republican-held seats and help us keep the majority on election night," said Matt Canter, spokesman for the Democratic Senatorial Campaign Committee. "Putting Republican-held seats in play is the key to success here."
The same poll showed Republican presidential nominee Mitt Romney up 10 percentage points over President Barack Obama, who won Indiana in 2008 but is given little chance this year. Republicans say the GOP shift will help carry Mourdock to victory.
"Indiana is a Republican state with Mitt Romney and (gubernatorial candidate) Mike Pence carrying the top of the ticket," said Brian Walsh, spokesman for the National Republican Senatorial Committee. "We're cautiously optimistic that we'll prevail."
Tightening races, new ad buys and a final dash for votes marked the closing days of a Senate campaign with a dozen competitive races, a significant number that remained as close as the presidential race. Republicans insisted that they had an opportunity in Pennsylvania to knock off first-term Democratic Sen. Bob Casey and a longshot chance to win New Mexico even though both campaign committees stopped spending in the state weeks ago.
Democrats were hoping for a strong Latino turnout in Arizona to help Democrat Richard Carmona take a GOP-held seat in his race against Rep. Jeff Flake.
Republicans were counting on grabbing the Democratic-held Nebraska seat although the contest between Republican Deb Fischer and former Democratic Sen. Bob Kerrey was tighter, reflected in the sudden infusion of money and visiting campaign help.
The Democratic-leaning group VoteVets was spending $275,000 on ads for Kerrey, the former Navy SEAL and Medal of Honor recipient in the Vietnam War. Another war hero, Republican Sen. John McCain of Arizona, campaigned for Fischer on Friday.
Kerrey picked up the endorsement of Vietnam veteran and former Republican Sen. Chuck Hagel on Thursday.
"She has a proven record of fiscal discipline, of balancing budgets, of working together as a team," McCain said of Fischer. "Her relationship with Sen. Mike Johanns — they would complement each other. They will not cancel out each other's vote. I'd also say that — and I hope that this is taken in the correct fashion — we do need more women Republicans in the United States Senate. And she represents, I think, something that a lot of women all over the country can look up to and aspire to."
In Connecticut, Obama made his first appearance for a Democratic Senate candidate in a campaign commercial, urging voters to back Rep. Chris Murphy in his race against wrestling empire executive Linda McMahon, who has spent more than $42 million of her own money.
The commercial is scheduled to begin airing Saturday.
Obama looks directly into the camera and says he knows Murphy and credits him with having "a real record of job creation" and "a jobs plan that puts the middle class first." McMahon has accused Murphy of not having a jobs plan.
Obama credited Murphy with supporting women's health issues and said he needs him "as a partner" in the Senate.