Vice President Joe BidenJoseph (Joe) Robinette BidenBiden: Trump family separation policy could make the US a pariah Elizabeth Warren can unify Democrats and take back the White House Giuliani doubles down on Biden comments: 'I meant that he’s dumb' MORE on Monday urged Democrats to give to their party in fundraising appeal, saying he has never seen "this many races in play."

In an e-mail to supporters of the Democratic Congressional Campaign Committee (DCCC), Biden said the competitive nature of the 2010 midterm elections should motivate donors to contribute in the final week of the campaign.

"Let me tell you something. I've been around campaigns for a long time, and I have never seen a midterm election with this many races in play," he said. "That's why my friends at the DCCC have a strategy in place to secure victory in these final days."

For months, Republican leaders have pegged the playing field in the House at about 100 seats, arguing the atmosphere is ripe for them to take control of the lower chamber. 

But Democrats have expressed confidence they will keep the GOP from making a net gain of 39 seats, which would hand them the House majority.

The vice president said Republicans are "putting everything they've got" in to the final stretch and challenged Democrats to "do the same." Biden has made more than 100 appearances for Democratic candidates this cycle, exhorting Democrats to go to the polls amid surveys showing an enthusiasm gap with Republicans. 

Biden, who has been in elected office for 37 years, said each dollar donated during the final eight days of the campaign "could be the difference between victory and defeat for another House Democrat."

The funds will go toward rapid response ads and "state-of-the-art voter contact efforts" for the final push before Election Day, and the goal is to raise $250,000 before Nov. 2, Biden said.

Biden has predicted Democrats would hold on to the House and Senate but appeared to hedge his bets last week by saying outside spending against Democrats made it tough to accurately predict the results.