HARRISBURG — Gov. Tom Wolf tapped to his top liaison to state lawmakers to become his next chief of staff on Thursday as her predecessor prepares to run for U.S. Senate.

Wolf, a Democrat, promoted Mary Isenhour, who was a top adviser to his successful campaign last year. She will become Wolf’s top aide in the midst of a three-week-old budget stalemate with the Republican-controlled Legislature that has left the administration without full spending authority.

Isenhour, 56, was also a former executive director of the state Democratic Party and ran the Pennsylvania leg of Hillary Clinton’s 2008 presidential campaign. Earlier, the Kansas native was the chief of staff to the Kansas Legislature’s Democratic floor leader.

Isenhour replaces Katie McGinty, who after six months in the job is expected to announce that she will run for the Democratic nomination to challenge Republican Sen. Pat Toomey in 2016.

Wolf gave McGinty credit for his administration’s accomplishments through its first six months, including overhauling Medicaid benefits in the midst of the program’s expansion and equipping state troopers with a drug designed to save the lives of people overdosing on heroin and other opioids.

“We’ve done so many things, we’ve only been in office for six months,” Wolf said during a news conference in his Capitol offices. “That’s attributed to the leadership Katie has provided. She has other things that she wants to do with her life, and I respect that.”

Republicans, who have huge majorities in the Pennsylvania House and Senate, welcomed McGinty’s departure.

For one thing, they were concerned about whether she was representing the governor during their meetings or the goals of someone who was running for office, Senate GOP spokesman Jennifer Kocher said.

“Whose agenda was she representing?” Kocher said.

They also felt stung by McGinty after she made an appearance at the Pennsylvania Press Club in May and accused Senate Republicans of backing pension legislation designed “to line their own retirement pocket.”

Senate Majority Leader Jake Corman, R-Centre, subsequently asked Wolf for an apology from McGinty, but did not get one. Wolf, who later vetoed the bill, and other opponents of the bill, including labor unions and Democratic lawmakers, did not echo McGinty’s criticism.