Story highlights Pence served six terms in the House, and most recently was a top-ranking leader

Pence will appear with Trump Tuesday night in an audition of sorts to be the billionaire's running mate

Washington (CNN) Many establishment Republicans on Capitol Hill have been reluctant to embrace Donald Trump's candidacy, but they are now talking up one of their own as a possible vice presidential pick -- Indiana Gov. Mike Pence, who served in House GOP leadership -- as a plus to the 2016 ticket.

"I have the highest, highest regard for Mike. He's a personal friend of ours and mine," House Speaker Paul Ryan told reporters on Tuesday, adding that he would withhold any more comment until Trump announces his pick.

Pence served six terms in the House, and most recently was a top-ranking leader who handled political messaging for the GOP conference. However, before leaders added him to the leadership table, he was frequently a thorn in their side. As chair of the conservative Republican Study Committee, he pushed for deeper spending cuts, was an early supporter of getting rid of so-called "earmarks" and at times criticized fellow GOP members.

Pennsylvania GOP Sen. Pat Toomey, who faces a tough re-election race, weighed in favor of the Indiana Republican. "I'm a big fan of Mike Pence. I think he'd be a great choice," he said.

One House Republican who has been skeptical of Trump told CNN: "Pence would really help things with the party establishment."

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