Ohio Gov. John Kasich has signed Thomas D. Rath, a longtime fixture in New Hampshire Republican politics, to lead his Republican presidential campaign efforts in the first-in-the-nation primary state, Kasich's campaign announced late Tuesday.

Rath, a party elder and former state attorney general who has served as a senior adviser to the presidential campaigns of Mitt Romney, George W. Bush and Bob Dole, will become Kasich's New Hampshire campaign co-chairman and senior national adviser.

"Our country needs Governor Kasich," Rath said in a statement. "He has a proven track record of balancing the federal budget, reforming our military and turning around one of our nation's largest states. Beyond his accomplishments, Governor Kasich governs in a way that includes everyone. He is sending our country the message that everyone deserves a chance, everyone deserves a voice, and he will help give it to them. That's a powerful message in New Hampshire and the right one for our nation."

Here's where Ohio Gov. John Kasich stands on the Iran deal, marriage, health care for the mentally ill and more, in his own words (Sarah Parnass/The Washington Post)

Kasich's landing of Rath's endorsement is a blow to Jeb Bush, the former Florida governor who has tried to lock up Republican establishment figures around the country but especially in New Hampshire, an early primary state where he is counting on a strong finish.

A late entrant in the presidential race, Kasich has been creeping up on Bush in polls in New Hampshire, buoyed by an aggressive television advertising campaign in the state on his behalf by an independent super PAC.

A Franklin Pierce University/Boston Herald poll of Republican primary voters released Tuesday showed Kasich running third in New Hampshire with 12 percent, behind Donald Trump with 18 percent and Bush with 13 percent. Sen. Ted Cruz of Texas was fourth with 10 percent.

Rath, a former member of the Republican National Committee, joins a growing team of Kasich supporters in New Hampshire. Former U.S. senator John Sununu is Kasich's New Hampshire campaign chairman, and has been one of the Ohio governor's most active supporters nationally.

"We're thrilled to have Tom join our team," Sununu said in a statement. "His expertise nationally and in New Hampshire will help our campaign build on the momentum we've established in New Hampshire and after the first debate. It's an honor to be working with Tom on behalf of Governor Kasich. He and other outstanding leaders will help guide us in the months ahead in New Hampshire and nationally."

Dan Balz contributed to this report.