As Chris Cillizza reports, the rising stars of the Republican Party have a lot on the line when they step to the podium in Tampa this week. But so, too, does the party itself. Two of the five scheduled speakers listed by The Fix — Sen. Marco Rubio (Fla.) and New Mexico Gov. Susana Martinez — are of color. And if the GOP ever hopes to stop its slide as a regional and reactionary collection of [fill in the blank]-phobic malcontents, it will have to figure out how to embrace the demographic changes it has resisted.

Other Republicans of color slated to speak include South Carolina Gov. Nikki Haley and Utah congressional candidate Mia Love. Louisiana Gov. Bobby Jindal was going to speak, but he has opted to stay in his state now that Hurricane Isaac appears to be literally following in Hurricane Katrina’s footsteps. These are the up-and-coming leaders of the Party of Lincoln. Yet, the New York Times reported Saturday, the Romney campaign is adopting a sharper tone against President Obama “to appeal to white, working-class voters.”

The Republican Party is leaving votes on the table. To watch its presidential ticket do so is like watching the GOP sign its own death certificate.

The clearest example of this is the party’s, and its nominee’s, extreme stance on immigration. Latinos are the fastest-growing demographic in the United States, with millions of new voters ripe for the Republican message. Nevertheless, Mitt Romney, the presumptive GOP nominee, is trailing the president among this key voting bloc. Hispanics have long voted more with Democrats than Republicans. President George W. Bush earned 41 percent of their vote in 2004. Sen. John McCain got 31 percent. Romney has reportedly set 38 percent as his target. Good luck.

How about African Americans? Bush was able to snag 11 percent of the black vote in 2004. McCain was able to get 9 percent. But as I highlighted last week, the NBC News-Wall Street Journal poll found 0 percent support for Romney among the African Americans surveyed. Remember, this is a poll, not a census. Romney’s stark result is among those contacted for the poll. It does not mean that Romney has no black support.

Part of the problem is that Romney is trying to unseat the first black president. Another part is the policy prescriptions that the Republican ticket espouses. And, let me tell you, Romney’s craven birther quip isn’t going to make it any easier to reach those black voters who might be wavering.

The clearest example of Romney leaving votes on the table came in the Logo TV-Harris Interactive poll released last week. Twenty-two percent of lesbian, gay, bisexual and transgender voters said they would be “more likely to vote for Romney” if he had the same position on gay rights as Obama does. With Obama snagging 67 percent of this group’s vote, a 22-point defection to Romney would have the two candidates virtually tied for the vote of LGBT Americans. In an election that is about evenly split, in an election where every vote counts and where every campaign is shaking the bushes to find a few more than the other guy to get that desired margin of victory, the GOP doing a great job of sealing its fate.