Pennsylvania Gov. Tom Wolf, a Democrat, on Thursday endorsed Labor Secretary Tom Perez in the intensifying race for chairman of the national party.

"Tom Perez is a proven leader with a record of delivering results for working families," Wolf said in a statement. "His vision for the party paired with his experience as an effective manager makes him well-suited to run the party as we move toward 2018."

Wolf, who is planning to seek reelection next year, has worked with Perez, who servers in the Obama administration and praised him as having "the unique ability to connect with people."

Wolf is the fifth Democratic governor to back Perez, joining Virginia's Terry McAuliffe; John Bell Edwards of Louisiana; John Hickenlooper of Colorado and Gina Raimondo of Rhode Island.

Rep. Keith Ellison of Minnesota, the first Muslim elected to the U.S. Congress, is running and has the backing of many of the liberal activists who were central to the presidential campaign of Vermont Sen. Bernie Sanders. Raymond Buckley, the state chairman of New Hampshire, has close ties to the Clintons and deep connections to the electorate: fellow members of the Democratic National Committee. Perez is the choice of the Obama legions in the party.

Wolf, like other party leaders, believes grassroots organizing is key to rebuilding the party after the crushing loss to Donald Trump. Perez said he is committed to that.

"The 2016 election demonstrated the importance of grassroots organizing and voter engagement across the country, but particularly in Pennsylvania," Perez said in a statement accepting the endorsement.

Members of the DNC will choose the new party chair in February.