The two leading contenders for the Democratic presidential nomination won't have to face off against the formidable -- and always unpredictable -- Vice President Joe Biden, who announced Wednesday afternoon that he won't make a late entrance into the Democratic race.Now, it's former Secretary of State Hillary Clinton and Vermont Sen. Bernie Sanders alone in the party's top tier of 2016 candidates.Here's a look at five ways Biden's decision will affect the presidential race:There's no doubt Biden's decision will help Clinton's poll numbers more than Sanders' in the short term.Polls have consistently shown Biden siphoned most of his support from Clinton. A CNN/ORC poll last week showed that Clinton held a 16 percentage point lead -- 45% to Sanders' 29% -- with Biden in the race and drawing 18% support. But with Biden removed from the list of candidates, Clinton's lead widened to 23 percentage points, at 56% to Sanders' 33%.Sanders has sought to run to Clinton's left. Biden, meanwhile, would have staked a claim on the legacy of President Barack Obama -- attempting to inherit much of the coalition that had swept him into office twice while also appealing to older blue-collar voters.Unless someone like Maryland Gov. Martin O'Malley shocks the political world by climbing out of the low single digits in the polls, Clinton now has a one-on-one race for the Democratic nomination.Still, longer-term, Biden's exit could help Sanders: He's now the only high-polling Democratic alternative to Clinton, which means if she stumbles or voters sour on her campaign, he stands to be the sole beneficiary.A Biden candidacy might have transformed the Democratic primary into a more free-wheeling campaign.Biden himself has admitted he's known for saying what he means -- which isn't exactly the reputation of Clinton, who's seen as stage-managed to a fault.Neither perception is entirely true: Biden, after all, is still a politician and subject to focus-group tested remarks. Clinton, meanwhile, has sought to bring a looser style to the trail, delivering a comfortable and confident performance in the first Democratic debate and poking fun at herself by appearing on NBC's "Saturday Night Live."