With Barack Obama poised to clinch the Democratic nomination, the Republican Party said Tuesday it will roll out arguments about why nearly 18 million people have already voted against the Illinois senator this year.

Republican National Committee (RNC) Chairman Mike Duncan and Deputy Chairman Frank Donatelli told reporters that, in the next few days, the GOP will also release research materials and videos showing Obama’s vanquished Democratic rivals — including Sen. Hillary Rodham Clinton (N.Y.) and former Sen. John Edwards (N.C.) — criticizing Obama’s “thin résumé.”

The message from the RNC was clear: The general election is under way, and the bull’s-eye is squarely on Obama.

The two Republican officials said the party would take the coming days to highlight what it sees as the facets of the Democratic Party that were resistant to or even skeptical of Obama’s experience and “misguided policies.”

In a strategy memo released to the media, the RNC outlined its reasons for claiming that Obama enters the general election campaign in weakened shape.

“Following all the uncertainty surrounding Barack Obama’s path to becoming the presumptive Democrat nominee, Obama is now faced with two very clear certainties as he ‘wheeze[s],’ as The New York Times puts it, across the finish line,” the memo reads. “First, he will inherit a fractured party that is deeply divided over his role as standard-bearer and his ability to be president. Second, he will inherit a national party apparatus that has been significantly outraised throughout the cycle.”

The memo notes that Obama has struggled after seizing the momentum from Clinton in February, and he lost key swing states. Many of his wins, the memo says, came in states where McCain is significantly outpolling Obama.

At times sounding like Clinton in recent weeks, Duncan and Donatelli repeatedly mentioned that Obama had struggled to win working-class, female, Hispanic and rural voters.

They did, however, stop short of echoing Clinton’s assertion that Obama was having trouble winning white voters in places like Pennsylvania, Ohio, Kentucky and West Virginia.

Duncan said the RNC would not broach the issue of race in the five months left before the general election.

“We hope and we expect that it will have no impact at all,” Duncan said. “It’s not something we’re going to raise at all, ever.”

Though Duncan and Donatelli repeatedly insisted that their party’s presumptive nominee, Sen. John McCain (Ariz.), has unified the Republican Party — Duncan said internal polling shows nine out of 10 Republicans supporting McCain — McCain has struggled to convert supporters of Rep. Ron Paul (R-Texas) and some hold-out supporters of former Arkansas Gov. Mike Huckabee even after securing the nomination.

“This is as unified as I’ve seen us,” Duncan said of his time as a Republican official. He added: “There are always outliers in this process, but we’re coming together very well.”

The Obama campaign responded that the RNC and McCain are in desperate need of changing the subject because there is an enormous appetite for change given the unpopularity of President Bush’s policies, which, they say, McCain is looking to extend for another four years.

“The McCain campaign knows they can’t win on substance since they’ve embraced George Bush’s policies, so it’s no surprise that they have also embraced Bush’s tactics,” Tommy Vietor, an Obama spokesman, said.