MADISON, Wis. (AP) — Former Wisconsin Gov. Tommy Thompson, a Republican elected to four terms starting in the 1980s, announced Monday that he will not run again in a bid to take on the Democratic incumbent in the battleground state.

A campaign by the 80-year-old Thompson would have put him on the ballot for the first time in a decade and 24 years after his last win. The winner of the Aug. 9 Republican primary will advance to face Gov. Tony Evers.

Thompson contemplated seeking yet another comeback in his unparalleled career in Wisconsin politics that spans more than half a century, even meeting last month with former President Donald Trump at Trump’s Mar-a-Lago resort to discuss it. Thompson said in a statement announcing that he would not run that it was a “very difficult decision.”

“I know I have the vision, drive and vitality to serve another term as governor,” Thompson said. “Wisconsin needs strong leadership to bridge political divides, care for our most vulnerable, set our economy on a path to succeed in the 21st-century, and again make us the shining star of the nation. I would have brought those qualities and commitment as governor.”

Thompson did not endorse anyone in the statement and did not immediately return a message seeking comment.

Thompson’s entry would have shaken up an already crowded Republican field that includes former Lt. Gov. Rebecca Kleefisch, businessman and former Marine Kevin Nicholson and state Rep. Timothy Ramthun. Last week, Madison businessman Eric Hovde decided against a run.

Ramthun has openly advocated for decertifying President Joe Biden’s win, even though Republican leaders and attorneys have said that would be illegal. Kleefisch and Nicholson also have supported Trump’s false claims that the 2020 election was stolen, and they have pushed to eliminate the bipartisan Wisconsin Elections Commission.

Kleefisch served eight years as lieutenant governor under Scott Walker between 2011 and 2018. Nicholson ran for U.S. Senate in 2018, losing the Republican primary to Leah Vukmir. She went on to lose to Baldwin.

Thompson last ran for office in 2012, when he won a Republican primary for U.S. Senate but then lost the general election to Democrat Tammy Baldwin. Before that, Thompson won election four times as governor — the most in state history — and served from 1987 until 2001. He left that year, midway through his fourth term, to become then-President George W. Bush’s secretary of health and human services.

Thompson has never been far from politics, briefly running for president in 2007 and in March completing a 21-month stint as interim president of the University of Wisconsin System.

Thompson’ political career began in 1966, when he was first elected to the state Assembly. He served there for 20 years before spending the next 14 as governor. He was U.S. health and human services secretary from 2001 to 2004.

His last two bids for public office failed. Thompson dropped out of the run for president in August 2007, five months before any state voted after his candidacy failed to generate momentum. While he won the 2012 Senate primary, he came out of it broke and eventually lost to Baldwin by more than 5 points.