Wisconsin Governor Scott Walker on Monday announced his official bid for the White House.

“I'm running for president to fight and win for the American people,” he said in a campaign video.

Walker, 47, is best known for declaring war against Wisconsin's public employee unions as a way to regain control over the state's budget. Shortly after taking office in 2011, he successfully pushed for a bill that repealed collective bargaining for most government workers. That led to an unsuccessful effort to recall Walker the following year.

Walker is the 15th candidate seeking the Republican presidential nomination.

He objects to marriage equality, a position he shares with his Republican rivals. But Walker has also called for a constitutional amendment defining marriage as a heterosexual union in response to the Supreme Court's recent ruling striking down gay marriage bans in all 50 states.

(Related: Scott Walker's wife, sons disagree with his opposition to gay marriage.)

According to The New York Times, Walker will start campaigning Tuesday in the four early nominating states of Nevada, South Carolina, New Hampshire and Iowa after holding a kick off rally in Wisconsin on Monday.