WASHINGTON — When two major candidates quit the presidential campaign on Wednesday, they freed up large blocs of voters who could tip the balance in still-close races in both major political parties.
For the Democrats, the decision by former North Carolina Sen. John Edwards to abandon his campaign could swing votes to both New York Sen. Hillary Clinton and Illinois Sen. Barack Obama, though probably more to her.
Edwards' supporters are similar in demographic profile and outlook to Clinton's. A smaller number were drawn to Edwards for his outspoken call to change Washington, which could lead them into the Obama camp.
For Republicans, the withdrawal of former New York Mayor Rudy Giuliani likely will push many of his supporters to Arizona Sen. John McCain. Giuliani endorsed McCain on Wednesday, and his appeal was largely to security-minded voters who are likely to warm to McCain as their second choice.
The sudden availability of new voters is arguably more critical for the Democrats, where Clinton and Obama are locked in a close competition heading into next week's Super Tuesday voting in 22 states.
Clinton likely has an edge among Edwards voters.
"The demographics of Edwards' supporters and the attributes they find most appealing in candidates should push them disproportionately into the Clinton camp," said Democratic pollster Mark Mellman, who isn't affiliated with any of this year's presidential campaigns.
"They tend to be white, lower-income, less well-educated and union members. That fits the white, downscale voters that fit the Clinton profile. They also think the most important thing is empathy, someone who cares about people like them."
Backing that up, a recent Associated Press-Yahoo poll found that about four out of 10 Edwards supporters said their second choice would be Clinton. About one out of four said their second choice would be Obama.
Obama's best chance to woo Edwards' supporters could be by emphasizing change.
Edwards based his campaign on an outsider promise to change the way Washington does business. He vowed a partisan fight for change while Obama offers a more civil approach, but both are seen less as Washington insiders than Clinton is.
Obama appealed to Edwards' supporters along those lines Wednesday, lauding both John and Elizabeth Edwards and working to link them to an Obama-like campaign for a different kind of politics.
"At a time when our politics is too focused on who's up and who's down, he made a nation focus again on who matters," Obama said of Edwards. "While his campaign may end today, the cause of their lives endures for all of us who still believe that we can achieve that dream of one America."
Clinton, too, appealed directly to Edwards voters Wednesday, saying, "I look forward to reaching out and trying to convince his supporters to support me."
For Republicans, Giuliani's endorsement of McCain likely means less than the fact that they tended to appeal to the same kinds of voters — moderate to liberal Republicans and security-minded voters, not so much religious-driven ones.
Republican pollster Whit Ayres said there's no doubt that most Giuliani supporters will switch to McCain.
"Rudy Giuliani is a less conservative candidate who emphasizes national security. That's the definition of a McCain Republican voter," said Ayres, who also isn't working for any candidate this year.
Already leading in the Northeast, McCain could gain strength by picking up Giuliani voters in such states as Connecticut, New Jersey and New York, which vote next Tuesday.
McCain's chief rival, former Massachusetts Gov. Mitt Romney, still has to compete with former Arkansas Gov. Mike Huckabee for more conservative, more religious voters.