Painter, who had previously formed an exploratory committee for a Senate run, will announce his candidacy in a news conference on Monday, his campaign announced.
Richard will be making an important announcement on Monday regarding his involvement in the U.S. Senate election in Minnesota. Stay tuned. pic.twitter.com/9fVEBxnoXq— Painter For Minnesota (@RWPMinnesota) April 26, 2018
Painter will challenge Smith in the Democratic Farm-Labor Party primary.
Smith was appointed by Gov. Mark Dayton to the seat after the resignation of former Sen. Al Franken.
Painter served as the White House’s chief ethics lawyer in the Bush administration from 2002 to 2005. He has been a professor at the University of Minnesota Law School since 2007.
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Painter has been a vocal critic of President Donald Trump on cable TV. He is also vice chairman of the Center for Ethics and Responsibility in Washington, which sued Trump for violating the emoluments clause of the Constitution. Its case was dismissed in December.
Smith said she intends to run for a full term in 2020, when the current term expires, as well as this November.
Minnesota has a second Senate race as Sen. Amy Klobuchar is running for re-election.
So far, state Sen. Karin Housley is the only Republican who has declared her candidacy to challenge Smith.