Senate Democrats shift $1M in South Dakota to support Rick Weiland against GOP's Mike Rounds

National Democrats plan to drop $1 million behind their candidate for South Dakota's open Senate seat, for the first time signaling that political operatives consider the race winnable and part of their drive to defend the Senate majority.

The investment from the Democratic Senatorial Campaign Committee will primarily go to television advertising for Democratic hopeful Rick Weiland, who is in a tough race against former Republican Gov. Mike Rounds for the seat being vacated by retiring Democratic Sen. Tim Johnson. Running as an independent is former Republican Sen. Larry Pressler.

Republicans are driving to gain six seats and the Senate majority. Rounds has been considered a favorite in the contest.

A businessman and onetime aide to former Sen. Tom Daschle, Weiland was not the national committee's preferred candidate in the race; they tried to recruit former Rep. Stephanie Herseth Sandlin. But Weiland and Pressler have both stayed competitive, benefiting from Rounds' recent struggles and the complex, multicandidate race.

Rounds has come under scrutiny for a state-run federal program that let foreign investors earn green cards in exchange for investments in rural job-creating projects. The South Dakota Board of Regents announced Tuesday that a 2008 lawsuit brought against South Dakota related to the embattled EB-5 visa program has been dismissed and the state would not be liable for potentially millions in damages.

Democrats have sought to make the EB-5 program a political issue, accusing a Rounds appointee of costing the state money by dragging it into litigation. The lawsuit began while Rounds was serving as governor. Rounds' knowledge about the lawsuit has become an issue in the Senate campaign. He has said he was not personally aware of the lawsuit when it was filed, but Democrats have said he must have known.

Mayday PAC, a political action committee, said earlier this week it would spend another $1 million to back Weiland with TV ads.