NEW ORLEANS (AP) — Candidates for seats in the U.S. Senate and House are readying for an expensive and heated battle to November, while GOP contenders continue their brawl for the party nomination in one district.

Republican Sen. David Vitter, having won the Republican primary by all but ignoring his opposition, heads for the Nov. 2 general election with more than $5 million — twice as much as his chief opponent, Rep. Charlie Melancon. Melancon easily won the Democratic primary Saturday. Polls generally give Vitter a double-digit lead.

Rep. Joseph Cao’s election to the New Orleans area’s 2nd Congressional District two years ago provided a rare lift to Republicans who had suffered losses in 2006 and 2008. Now, with Republicans nationwide threatening to take back the House, the question is whether Cao can pull off a second victory in the mostly black, mostly Democratic district.

Unsettled is the final matchup in southeastern Louisiana’s 3rd District. It’s a Republican-leaning district, but Melancon won three terms there.

After a nasty campaign, New Iberia attorney Jeff Landry fell just short of the majority needed for outright victory in Saturday’s 3rd District primary, so he’ll face former Louisiana House Speaker Hunt Downer in an Oct. 2 runoff. The winner will advance to the general election against political newcomer Ravi Sangisetty, an attorney who has shown some fund raising prowess.

As he shoots for the Senate, Melancon casts himself as an anti-abortion, pro-gun, fiscal conservative and centrist Democrat who can work across party lines.

That role has worked in the past for Democrat Mary Landrieu, who is in her third Senate term. But Melancon, familiar to many in southeastern Louisiana, doesn’t have Landrieu’s statewide name recognition. And, says University of New Orleans political scientist Ed Chervenak, anti-Obama sentiment in the state is helping Vitter.

“He’s the kind of primary opposition mouthpiece against the Obama administration and that seems to be where voters in Louisiana are,” Chervenak said. “They’re very hostile to the President and, so, Vitter’s tapping into that anger.”

Melancon’s vote for Obama’s stimulus bill has been a prime target of Republicans.

“Spending is out of control, our taxes are too high and the government is far too involved in our everyday lives. Each step of the way, Charlie Melancon has been a consistent vote for this reckless Obama agenda,” Vitter said Monday in a fundraising e-mail.

Aside from describing Vitter as ineffective, Melancon has showcased another campaign theme that attempts to cast Vitter as “hostile to women.”

Melancon’s campaign ads have already mentioned the 2007 scandal that erupted when Vitter’s phone number was linked to a Washington call girl ring; Vitter admitted only to a “serious sin” but won’t answer questions about it. More recent news that Vitter kept on his staff for two years an aide accused of a violent attack on a woman have also been part of the campaign, along with a Vitter vote against an equal pay law.

Melancon acknowledged he has a tough race in trying to unseat Vitter.

“David Vitter may not have much of a record to run on, but he does have one thing: money. He’s built up a sizable war chest that he’ll be using to distract Louisiana voters from his hostility toward women, veterans and Louisiana families,” Melancon said an e-mail to supporters Monday.

In the 3rd District, Landry and Downer both have said they want to focus on the issues, but after the mudslinging so far, it appears unlikely. That could help Sangisetty.

“What we might see is the two Republicans eat each other alive prior to the Republican Party runoff. And so that would benefit the Democrat,” Chervenak said. “They’re going to be spending money attacking each other that they could use to attack the Democrat.”

Landry has slammed Downer for his decades-long political career as a Democrat. Downer switched parties in 2001, and after that worked as a legislative lobbyist for Democratic former Gov. Kathleen Blanco.

Downer has hit Landry on a civil lawsuit involving a small business Landry once owned — and that Landry uses to tout a pro-business record. Landry paid more than $30,000 in the lawsuit, which accused him of fraudulent business practices.

Both men exchanged attacks about the other’s time in the Louisiana National Guard. Downer accused Landry, who served for 11 years and left as a sergeant, of misrepresenting his service when he calls himself a veteran of Operation Desert Storm though he never served overseas. Landry accused Downer, a retired major general, of playing politics to achieve his rank.

To overtake Landry, Downer likely would need to pick up much of the support given to the third-place Republican in the race, Kristian Magar, or persuade scores of additional GOP voters to show up for the runoff election who didn’t cast ballots in the primary.

In the 2nd District, which includes much of New Orleans and part of Jefferson Parish, state Rep. Cedric Richmond had the backing of Mayor Mitch Landrieu and others in the political establishment in the primary and scored an easy victory over three opponents.

He’ll face Cao, whose surprise victory and compelling life story — he fled Vietnam as a child during the war, rose to success in the United States and became the first Vietnamese-American in Congress — was a bright spot for Republicans in a year when Obama was elected and Democrats were solidifying their hold on Congress.

Cao had two advantages in the 2008 race. The incumbent, longtime Congressman William Jefferson, faced a corruption indictment that would eventually lead to his conviction, and the election was delayed by two hurricanes, making for a low-turnout affair.

Republicans are raising questions about Richmond’s ethics. Among their attack points is the state Supreme Court’s six-month suspension of Richmond’s law license in 2008. The court found that, when Richmond signed up to run for a City Council district seat five years ago, he had falsely sworn to being domiciled in the district.