Sam Brownback, the beleaguered governor of Kansas whose aggressively conservative fiscal polices turned some fellow Republicans against him, will be nominated to serve as ambassador at large for international religious freedom, the White House said in a statement on Wednesday.

Mr. Brownback, 60, represented his home state in Congress before being elected to two terms as governor beginning in 2011.

On Twitter, Mr. Brownback wrote on Wednesday: “Religious Freedom is the first freedom. The choice of what you do with your own soul. I am honored to serve such an important cause.”

Melika Willoughby, a spokeswoman for Mr. Brownback, said he remained Kansas’ governor as of Wednesday night. She said there would a news conference on Thursday afternoon, but declined to comment beyond Mr. Brownback’s Twitter statement.

Lt. Gov. Jeff Colyer, a doctor from suburban Kansas City who previously served in the State Legislature, is expected to take over as governor if Mr. Brownback’s nomination is confirmed by the United States Senate.

In the ambassadorship, Mr. Brownback would lead the Office of International Religious Freedom, which is under the umbrella of the State Department and charged with promoting religious freedom as a foreign policy objective.

Mr. Brownback’s popularity has plummeted in recent years as the state slashed services and struggled to meet its revenue projections, problems that many attributed to Mr. Brownback’s signature tax-cutting doctrine. Despite Republicans’ dominance in Kansas, the party suffered losses in last year’s legislative elections.

Kansas lawmakers rolled back Mr. Brownback’s tax policies this year, with Democrats and moderate Republicans banding together to override the governor’s veto and raise taxes. Mr….