Scott Walker to Enter U.S. Presidential Race

Republican Scott Walker, the Wisconsin governor who earned national attention for his protracted battle with labor unions, will file paperwork Thursday to launch a 2016 U.S. presidential campaign, an aide said.

"After hearing from countless Americans during the testing-the-waters phase, Governor Walker this morning will file his papers of candidacy" with the Federal Election Commission, a Walker aide said.

He will then host a campaign launch event in Waukesha, Wisconsin on July 13th, according to the aide.

The 47-year-old state executive is currently second place in polling, behind former Florida governor Jeb Bush and slightly ahead of Senator Marco Rubio and retired neurosurgeon Ben Carson, according to an aggregate compiled by RealClearPolitics.

Walker becomes the 15th major Republican to join the crowded field. A 16th, Ohio Governor John Kasich, is expected to enter the race later this month.

Former secretary of state Hillary Clinton is the prohibitive favorite to win the Democratic nomination in the race to succeed President Barack Obama.