Obama spoke at the home of Tom Sullivan, who founded Lumber Liquidators.

Obama said that sometimes Republicans are open to working with him, on topics such as immigration reform. But, the president continued, "all too often, we're not getting cooperation from the other side."

"It'd be a lot easier if I had a Democratic House and a Democratic Senate," Obama said. "We've got a lot more work to do. It's going to be absolutely critical that everybody here feels the same urgency ... over the next year."

If Democrats keep the Senate, Obama said, he will be able to "appoint outstanding judges to the federal bench" and pass his agenda on climate change.

At a second fundraiser, in the home of philanthropist Joseph Blount, the president warned of the fatigue common in midterm elections, where, Obama said, “our turnout falls off.”

"You can't just play in the fourth quarter, you've got to play in all the quarters," he said, according to a pool report.

-This report was updated at 9:00 p.m.