NASHVILLE, Tenn. >> Republican U.S. Sen. Lamar Alexander of Tennessee announced today that he won’t seek re-election in 2020, a decision that gives the red state its second open Senate contest in two years.

Alexander said in a news release that he’s deeply grateful for being elected to serve more combined years as governor and senator than anyone else in Tennessee. But the 78-year-old said it’s now time for someone else to have that privilege.

The long-tenured Tennessee leader’s decision raises speculation that popular Republican Gov. Bill Haslam could make a run for the Senate. Haslam declined to run for the seat that Republican Sen. Bob Corker is vacating and that Republican Sen.-elect Marsha Blackburn won in November. Haslam is leaving office in January due to term limits.

Republican strategist Ward Baker, who led Blackburn to victory, said President Donald Trump spoke with Alexander on Sunday night and wanted him to seek re-election, but that Alexander wanted to go out on top after serving a long time.

A Maryville, Tennessee native, Alexander served as governor from 1979 until 1987, and helped bring the auto industry to the state. He was elected to the U.S. Senate in 2002 and was re-elected in 2008 and 2014.

He developed a reputation as a consensus builder, including recent laws to address the opioid crisis and overhaul the way music is licensed and songwriters are paid. He also teamed with Democratic Sen. Patty Murray of Washington to try to stabilize health insurance markets after Republican failed to repeal and replace the Affordable Care Act, though the effort has so far come up short.

“I have gotten up every day thinking that I could help make our state and country a little better, and gone to bed most nights thinking that I have,” Alexander said in his statement. “I will continue to serve with that same spirit during the remaining two years of my term.”

Alexander also was a candidate for the Republican nomination for president in 1996 and 2000 and was U.S. education secretary from 1991 to 1993 under George H.W. Bush.

After leaving the governor’s office, Alexander also served as president of the University of Tennessee from 1988 to 1991.

Alexander had shown signs that he might have been gearing up for another re-election. For instance, his campaign had just ordered up a poll that found he was still very popular among Tennessee Republican primary voters.

Now Alexander’s announcement sets off a scramble for candidates to replace him just a month after the race to replace Corker was finally settled. In the state’s most expensive race ever, Blackburn won by about 10 percentage points against former Democratic Gov. Phil Bredesen.

Corker on Monday called Alexander “the legislator of the decade because of the effective way he has worked across the aisle to pass legislation that directly affects the lives of so many throughout our state and around the country.”

Tom Ingram, a Tennessee GOP strategist with stints as Alexander’s chief of staff as governor and in the Senate, said he believes Haslam’s decision controls who else considers entering the race.

“I don’t think he’s going to rush a decision,” Ingram said of Haslam. “He’s going to take some time and really think about it.”

Another name that has come up for a possible GOP Senate bid is Mark Green, a newly elected congressman who hasn’t taken office yet.

Alexander attended the unveiling of Haslam’s official gubernatorial portrait Monday shortly before the announcement. The senator did not mention his re-election decision at the event.

In a statement afterward, Haslam did not touch on whether he was interested in running to replace Alexander.

“No one has served our state longer as a governor and senator, and few, if any, have served it better than Lamar,” Haslam said.

In October 2017, Haslam decided against running to replace Corker in the Senate, saying he wanted to remain completely focused on his job as governor. He said he loved being a mayor and a governor, but did not feel the same call to run for Senate at that point.

Blackburn announced her bid for the seat later that day.