Biden will watch Dem debate in DC
Biden will host a high school reunion and then watch the debate at his home at the Naval Observatory in Washington, an aide said. 
The vice president was not expected to participate in the debate, but speculation ran rampant in recent days that Biden could make a surprise appearance and jump into the race. 
CNN, which is airing the debate, held out hope that Biden would attend. It crafted its debate rules to allow Biden to participate if he accepted an invitation as late as Tuesday.
The network even brought an extra lectern to accommodate Biden.
The vice president is participating in meetings at the White House with President Obama and Attorney General Loretta Lynch.
Many political observers have suggested the days surrounding contest are an opportune time for Biden to jump into the race. The Draft Biden super-PAC ran a new ad Tuesday urging him to jump into the race. 
White House press secretary Josh Earnest on Tuesday conceded Biden is facing time pressures to make a decision, but added the White House would allow him to make “an announcement on a time frame of his choosing.”
“That is a matter of simple physics when it comes to time and space,” Earnest said when asked about the ticking clock for Biden. “But in terms of what sort of pressures he is facing in terms of his time frame for getting into the race, those are pressures he’ll evaluate independently.”