Sam Brownback, the beleaguered governor of Kansas, 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, a farm boy from eastern Kansas, represented his home state in Congress before being elected to two terms as governor beginning in 2011.

On Twitter, Mr. Brownback posted 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.”

The Run-Up

The podcast that makes sense of the most delirious stretch of the 2016 campaign.

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

Lt. Gov. Jeff Colyer is expected to fill in for Mr. Brownback if his 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 blamed on 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. Brownback has also clashed with some members of his own party on Medicaid expansion under the Affordable Care Act, which he vetoed this year.

Mr. Brownback’s policies were seen as a test of the Republican doctrine that lowering the tax burden on businesses would attract employers to the state and grow the economy. It was being closely watched by conservatives across the country to see how it might affect Kansas. But the growth never came.

Mr. Brownback will leave Kansas at a time of uncertainty over funding for public education. The Kansas Supreme Court is expected to rule soon on the constitutionality of the state’s new school funding mechanism.

“He leaves behind a legacy of failed leadership,” said Melissa Rooker, a Kansas House Republican who has been in the moderate wing and a frequent opponent of Mr. Brownback’s policies. She said she did not know what to expect from Mr. Colyer because he was not involved in the day-to-day dealings of the Legislature.

State Representative Jim Ward, the Democratic leader in the Kansas House, said he was “not surprised” to hear of the appointment, which has been rumored in Topeka for months.

“I’m not going to miss him,” Mr. Ward said. “He has left a state in carnage and destruction.”

Mr. Ward said that he believed the governor “had the background” for his new ambassadorship, but that “he hasn’t embraced diversity” consistently in Kansas. “Hopefully, this job that he’ll step into, he’ll realize that Americans are of all kinds of faith,” he added.

Ron Ryckman Jr., a Republican and the House speaker, said Mr. Brownback was “uniquely qualified” for the ambassadorship. “I wish him all the best in his new post and would like to express my gratitude for his extensive service to the State of Kansas.”

In announcing the intended nomination, the White House noted that Mr. Brownback, a former United State senator and representative, “worked actively on the issue of religious freedom in multiple countries and was a key sponsor of the International Religious Freedom Act of 1998.”

Mr. Brownback, a father of five, has also been a lawyer, a state secretary of agriculture and a one-time presidential candidate.