President Obama and former President Clinton will address Senate Democrats during their annual retreat next week, according to a Democratic aide.

Obama usually addresses the retreat, and Sen. Charles Schumer (D-N.Y.) invited Clinton to appear this year.

The Democratic lawmakers will gather at the Washington Nationals baseball team's stadium, just more than a mile south of the Capitol complex.

The appearances from the current and former presidents will take place ahead of the 2014 midterm elections, where the party faces a tough fight to keep hold of the Senate. Democrats are defending 21 of the 36 Senate seats up for reelection in the fall, and must win 16 of those races to maintain control of the upper chamber. Retirements in red states like South Dakota, West Virginia and Montana have complicated that task, and Sens. Mark Pryor (D-Ark.), Mark Begich (D-Alaska), Mary Landrieu (D-La.) and Kay Hagan (D-N.C.) are facing tough reelection battles.

Landrieu and Hagan raised eyebrows when they declined to attend events with Obama in their home states in recent months, suggesting the president might be viewed as a liability by the lawmakers.

On Tuesday, Senate Majority Leader Harry Reid (D-Nev.) said he would encourage vulnerable Democrats to still campaign with the president.

"Barack ObamaBarack Hussein ObamaThe true commander in tweet Meghan Markle's pre-royal 'finishing lessons' and an etiquette of equality Hannity on Acosta claim he was tough on Obama: 'Only thing missing were the pom-poms' MORE is personally a very popular guy. And people love this man. They love his family," Reid told CNN. "Of course, with what the Republicans have been doing, trying to denigrate him with what's happened with the rollout of ObamaCare, but things, even this week, his numbers are going up again."

On Thursday, White House press secretary Jay Carney dismissed concerns about Democrats' unwillingness to appear with the president.

"He obviously supports Democratic candidates, both incumbents and challengers across the country, and I think we’ve amply demonstrated that support already and he will continue to do so," Carney said.