For the last few months, polls have suggested that Republicans would win back the House, and perhaps even the Senate in November's mid-term elections. But new polls leave the GOP more worried about Election Day.

Democrats — who did not expect to do well this midterm, anticipating even worse losses than majority parties usually suffer in midterms because of the failing economy — are beginning to see glimmers of hope that their losses might not be as bad as they feared.

Some Democratic incumbents have begun to raise questions about their Republican challengers and shift the focus of voters away from contentious national issues like health care, bailouts and President Obama's performance.

Republicans still carry substantial advantages as they move into the final month of the fall campaign, but the resilience of vulnerable Democrats is complicating Republican efforts to lock down enough seats to capture the House and - with luck - the Senate.

Races typically tighten in the final month as voters on both sides become more engaged, and now that October is here, both sides are unleashing everything they've got.

The chances of a Republican takeover in the House remain far greater than in the Senate, according to a race-by-race analysis by The New York Times. But enough contests remain in flux that both parties head into the final four weeks of the campaign with the ability to change the dynamic before Election Day on November 2nd.

Polls show Democratic Sen. Barbara Boxer, who'd been running neck-and-neck with GOP challenger Carly Fiorina over the summer, has reclaimed her lead, which has caused Republicans to pour $2 million into the contentious California Senate race.

Republican ads in Connecticut attack Democratic Senate candidate Dick Blumenthal (running for the retiring Chris Dodd's seat) about his claims to have served in Vietnam. ("Would you lie about serving in a war? Dick Blumenthal did. Again and again.")

Democratic ads in Louisiana attack Republican Senator David Vitter and his ties to prostitution. ("His number appeared on the D.C. Madam's phone list.")

But some may have hurt themselves.  Tea Party darling and Christian Conservative Christine O'Donnell appears to have embarrassed herself and her fledgling Senate campaign after releasing her first TV ad.

"I'm not a witch," O'Donnell deadpans into the camera at the start of the 30-second ad released Monday.

O'Donnell's ad puts her in the hallowed hall of political denials, which include President Richard Nixon's "I am not a crook," and President Bill Clinton's "I did not have sexual relations with that woman."

The witch controversy stems from comedian Bill Maher, who has been releasing embarrassing clips of the wannabe senator from his 1990s show "Politically Incorrect" since her primary win last month, including one where she admits she dabbled in witchcraft.

"One of my first dates with a witch was on a satanic altar, and I didn't know it. I mean, there's little blood there and stuff like that," O'Donnell said. "We went to a movie and then had a little midnight picnic on a satanic altar."

Other clips show O'Donnell referring to evolution as a myth and saying her love of meatballs kept her from becoming a Hare Krishna.