Biden warns Dems of threat of GOP retaking Senate majority

Vice President Joe Biden sought campaign cash for Senate Democrats on Tuesday by reminding supporters of how close Republicans are to winning a majority in 2012.

Biden, in an e-mail on behalf of the Democratic Senatorial Campaign Committee, noted the 23 seats Senate Democrats must defend in 2012, sought donations ahead of the end-of-March fundraising deadline.

"Democrats are defending 23 seats in 2012, five of which are open. Republicans only need to pick up four to take control of the Senate," Biden wrote in a fundraising e-mail.

The vice president called the Senate the "firewall" for Democrats against Republican inroads and called the 2012 Senate elections "the toughest electoral climate we’ve seen in a long time."

Republicans are optimistic that given the broad turf Democrats must defend in 2012, and given the GOP's own recruitment of top-tier candidates in Senate races so far, they'll make inroads and possibly win the Senate majority in the congressional elections next fall. Republicans would need to win four seats as long as they hold their own seats.

Biden set up the fundraising deadline at the end of March as a crucial metric of Democrats' strength. Last month's figures emerged in the past week, showing the DSCC as having bested its GOP counterpart in February.

"The end of the month’s FEC deadline is a crucial test of our strength," Biden wrote. "By giving to the DSCC, you have the power to prove to the pundits and our opponents that grassroots Democrats are standing together to defend our firewall."