Democratic startegists have been salivating at the opportunity to fight the fall election with Donald Trump as the Republican nominee, and with a new ad out today, we can begin to see why.

A new Democratic Senatatorial Campaign Committee ad shows clips of Trump using crude language and mocking a disabled reporter, and intercuts them with vulnerable senators playing footsie with Trump or saying that they'd support him as nominee.

Among the candidates are: Sens. John McCain of Arizona, Mark Kirk of Illinois, Ron Johnson of Wisconsin, Kelly Ayotte of New Hampshire, Richard Burr of North Carolina, Rob Portman of Ohio, Pat Toomey of Pennsylvania and Roy Blunt of Missouri.

The ad accuses them of "running for U.S. Senate in lock step with Donald Trump."

The Republican Senate majority is in danger in 2016, because the party will be forced to defend all the seats won in 2010, a wave election year. Also, 2010 was a midterm election, when the electorate is more favorable to Republicans. Given that this is a presidential election year, turnout in states such as Illinois, Wisconsin, Ohio, Pennsylvania and Florida is likely to be much more favorable to Democrats than it was six years ago.

To recapture the Senate, Democrats need to gain five seats — or just four if they also win the presidency.

This ad was brought to my attention by liberal Washington Post blogger Greg Sargent, who writes, "This represents an elaborate trolling exercise — it is a Web video whose timing seems deliberately chosen to rub salt in the GOP's festering Trump wound at exactly the moment when he's poised to rack up big victories."