Republican U.S. Rep. Greg Gianforte reportedly filed papers to run for governor in Montana, signaling his intent to enter a key 2020 gubernatorial race.

Gianforte, Montana’s only member of the U.S. House of Representatives, filed paperwork on Thursday with the state Political Practices Office, KTVH reported. “After many conversations and encouragement from Montanans across the state, Greg has filed paperwork to launch a campaign for governor,” a spokesman for Gianforte told the outlet, confirming he would formally announce his campaign this week.

The Republican has long signaled interest in the gubernatorial race to succeed term-limited Gov. Steve Bullock (D). Gianforte “met with members of House GOP leadership earlier this year to make them aware of his potential bid but had not solidified his decision at that time, two senior leadership sources said,” according to the Hill.

Gianforte first came to Congress in 2017 after winning a special election against Democrat Rob Quist for a seat vacated by Republican Ryan Zinke, who left to become President Trump’s interior secretary. Just before election night, Gianforte made headlines when he body-slammed a reporter from the Guardian. The Montana Republican ultimately pleaded guilty to a misdemeanor assault charge.

One of the wealthiest members of Congress, Gianforte funded anti-choice organizations through his family foundation before heading to Washington. A Rewire.News analysis of the Gianforte Family Foundation’s charitable giving between 2005 and 2014 found that the foundation gave more than $1.6 million to anti-choice organizations such as Focus on the Family, the Alliance Defending Freedom, the Family Research Council, Students for Life of America, 40 Days for Life, the Heritage Foundation, and the Montana Family Institute.

Gianforte lost a bid for the governor’s office in 2016. He was endorsed in that race by anti-choice group Susan B. Anthony List, which described him in a press release as “a pro-life advocate and longtime supporter of pregnancy resource centers.”

In a 2017 interview with the Billings Gazette, Gianforte reiterated his anti-choice view. “I am pro-life. We should have a culture that values life from conception to natural death,” Gianforte said. He went on to voice his support for 20-week abortion bans, which are based on the false claim that a fetus can feel pain at that point in a pregnancy.

Since joining Congress, Gianforte co-sponsored several anti-choice bills, including the 2017 “Life at Conception Act,” a personhood measure that would have given constitutional rights to fertilized eggs, embryos, fetuses, and clones—thus banning abortion and some forms of contraception. He also co-sponsored Rep. Steve King’s (R-IA) “Heartbeat Protection Act of 2017,” a near-total abortion ban that would have prohibited abortion around six weeks into pregnancy, before many people know they are pregnant.

The field for the 2020 Republican nomination for governor in Montana is already crowded. State Attorney General Tim Fox, state Sen. Al Olszewski, and Montana Secretary of State Corey Stapleton have announced bids so far. No Democrat has jumped into the race yet.

The Cook Political Report rates Montana’s gubernatorial race as a “toss up.”

Gianforte’s entry into the race for governor opens up his congressional seat. A Democrat hasn’t held Montana’s House seat since 1994, according to Roll Call.