President Barack Obama is trying to convince Democratic donors to open their wallets by telling them liberals like Massachusetts Sen. Elizabeth Warren would be the “driving force” if control of the Senate changes hands.

Sending Hillary Clinton to the White House won’t matter much unless Democrats control some legislative levers, according to Obama’s pitch. For that to happen, the party needs to fill its campaign war chest.

“Some of the most important achievements we’ve won together since I’ve been president wouldn’t have been possible without a Democratic majority in the Senate,” Obama writes in a Democratic Senatorial Campaign Committee mailer.

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“The bottom line: If we want to see real change continue after I leave office, then we must win back the majority in the Senate this November,” the president writes.

Obama name-drops Sen. Michael Bennet who is running for re-election in Colorado, and Democratic candidates Rep. Tammy Duckworth, former Sen. Russ Feingold and Katie McGinty, who are trying to pick up Republican-held seats in Illinois, Wisconsin and Pennsylvania respectively.

“These are impressive candidates, but they’re up against extremely well-funded opposition,” Obama writes. “And conservative billionaires have signaled that they plan to focus more and more of their attention on Senate races, planning to spend millions of dollars on attack ads designed to protect Republicans’ hold on the Senate.”

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Obama tells potential donors their financial help is needed to push back against GOP “false attacks,” while also helping grass-roots efforts like the ones that propelled him to victory in 2008 and 2012.

And with political observers already wondering what role Warren and the liberal wing of the Senate Democratic caucus, which also includes Vermont independent Sen. Bernie Sanders, would play should the party take back the chamber, Obama sheds a light on the answer.

“Progressive champions” like Warren and Bennet “will be a driving force behind our new majority,” Obama writes.

Contact Bennett at johnbennett@cqrollcall.com. Follow him on Twitter @BennettJohnT.