The radio ad argues the incumbent Republican is important regardless of who wins the White House.
Money is being shifted to the North Carolina and Missouri Senate races.
Portman joked with Cincinnati Enquirer staffers beforehand that they should "make a big circle."
The labor union had previously backed Democrat Ted Strickland.
Republicans are attacking North Carolina's Deborah Ross over her work at the ACLU.
“He is asking us to let him get rich scamming America," Reid said.
Jason Kander is trailing Sen. Roy Blunt in polls.
Democratic opponent Tammy Duckworth has yet to release her medical files.
The Republican incumbent leads Ted Strickland by 17 points.
Ayotte faces a tough reelection battle against Democratic Gov. Maggie Hassan.