— -- NOTABLES

--5 WAYS THE FIRST DEMOCRATIC DEBATE CHANGED THE 2016 PRESIDENTIAL RACE. The stage may have been less crowded, but the stakes were just as high. The five candidates on stage Tuesday night for the first Democratic debate -- less than half of the 11 on stage for the most recent Republican debate -- had a lot to prove. Frontrunner Hillary Clinton reasserted herself as the dominant force in the race. Meanwhile, Bernie Sanders played to his base, but likely didn't do much to expand it. The other three -- Martin O'Malley, Jim Webb and Lincoln Chafee -- likely didn't do anything to earn them a share of the spotlight, especially as speculation continued to swirl around the potential candidacy of Joe Biden. ABC's RYAN STRUYK takes a look at where we can expect the Democratic race to go from here. http://abcn.ws/1K9lyO2

-- BIDEN 'PROUD' OF HOW DEMOCRATIC CANDIDATES PERFORMED: Vice President Joe Biden, still wrestling with a decision to enter the 2016 presidential race, said yesterday he was impressed with the performances of the Democratic candidates at last night's primary debate, ABC's ARLETTE SAENZ notes. "I thought they all did well," Biden said in response to questions from reporters following a White House event on infrastructure projects. Despite growing speculation over the past weeks that Biden would participate in the first debate, he stayed in Washington as the other contenders sparred on stage in Las Vegas. http://abcn.ws/1Lb0LgS

--WHAT IS JOE BIDEN DOING? This morning he will deliver opening remarks at a roundtable discussion for Domestic Violence Awareness Month and he hosts a lunch with South Korean President Park Geun-hye at the Naval Observatory.

--ANALYSIS -- ABC's RICK KLEIN: At a certain point, deciding not to decide is its own decision. The fact that Vice President Joe Biden wasn't on stage when Democrats saw their field assemble -- for what ended up being a well-received debate - spoke volumes to party regulars who were already frustrated that Biden has blown through his own self-imposed deadlines for declaring his intentions. More than a few Democrats who made the trip to Las Vegas made the point that, without questioning Biden's motives or the genuine nature of his internal conflicts, his indecision had the impact of signaling that he thought something was lacking in the 2016 choices. Then the debate happened, and few Democrats seem to share the sentiment that the field would earn an incomplete. Add to that the lack of an obvious Biden base, the far-behind campaign infrastructure, and the vice president's unimaginably complicated personal and family situation, and the prospects of a Biden candidacy slip further from reality. If the vice president's calculation was going to be based at all on Democrats' begging him to run, that has to come out of the equation now.