Louisiana Primary: Vitter's First Post-Madam Test In a State Changed By Katrina

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While most of the country has its eyes on Louisiana for the five-year anniversary of Hurricane Katrina, voters in the state will be headed to primary polls on Saturday.

It is the first chance Louisiana Republicans have had to pass judgment on Sen. David Vitter, one of the most scandal-ridden lawmakers on Capitol Hill. But voters in Louisiana seem willing to forgive if recent polls are any indication.

Long a family values candidate, Vitter admitted in 2008 to having visited a prostitute while he was in Congress. And more recently, as ABC reported first, Vitter came under fire from women's groups for continuing to employ a staffer who pled guilty to abusing his girlfriend.

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"It takes more than one sex scandal to bring down a Louisiana politician," said John Maginnis, who writes for the LaPolitics.com website and forsees a sweeping Vitter victory Saturday.

A retired Supreme Court Judge, Chet Traylor, filed paperwork to oppose Vitter at the last moment, but Traylor's campaign has seemingly not taken off. He has not raised much money, has not put any TV ads on the air, and has not been able to enter the conversation. Plus – and this is an amazing irony – Traylor has been dogged by allegations of infidelity. He is involved in a relationship with the estranged wife of his stepson.

Watch his interview by Jonathan Karl and Rick Klein here.

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ABC's Cokie Roberts, a Louisiana politics expert, said Vitter was also inoculated against the effect of his infidelity because his wife stood by him during his admission in 2007 and after.

"In Louisiana they're saying at least he didn't covet another man's wife," said Roberts, referring to Traylor. "(Vitter's) wife stood by him and that's huge in this even among his religious conservative base. We've learned it from Elizabeth Hamilton, wife of Alexander, on down."

Founding Father and Federalist Papers author Alexander Hamilton admitted to infidelity in 1797 in order to clear his name against corruption allegations.

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Melancon the Likely Dem for Senate, A Wash in the House

In November, the Republican is likely face Democrat Charles Melancon, a congressman who has distanced himself from his party with votes against health care and the climate bill.

Vitter leads Melancon in hypothetical general election polls. Roberts said the state has changed since Katrina. More affluent conservatives and whites have returned to the state.

"The city of New Orleans certainly has rebuilt in all kinds of ways. It looks beautiful. But when people talk about the 80 percent that has returned, the 20 percent that has not is predominantly black," she said.

"It's a less black city and so a less Democratic state. That's just reality," she said.

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Read more about the rebuilding of Katrina here.

Four Democrats are squaring off for the right to challenge Rep. Ahn (Joseph) Cao in November. Cao is a Republican in the heavily Democratic district. He voted in favor of the House Democrats version of health reform -- the only Republican to vote for a version of the bill. But Cao voted against the final version that became law. He's the fluke Congressman who took over Rep. William Jefferson's seat. Jefferson is now in prison after being convicted of taking bribes. Democrats expect to take the seat back -– a rare anticipated pickup –- in November.

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It'll be a wash, however. Democrats have little chance of holding Melancon's seat.

ABC News Political Director Amy Walter Contributed to this report