Representative David Trone, Democrat of Maryland, said he was set to launch a campaign for the Senate on Thursday, joining a race into which he is expected to pour tens of millions of dollars from his personal fortune in an effort to capitalize on a rare opportunity to seek an open seat in the deep-blue state.
Just days after Senator Benjamin L. Cardin, who has held his seat since 2007, announced he would not seek re-election, Mr. Trone, 67, a third-term congressman from Potomac, said he had assembled a campaign team and cut an advertisement that emphasizes his roots growing up on a Pennsylvania farm and building a fortune after founding a lucrative alcohol retail business, Total Wine & More.
In an interview, Mr. Trone, who is in his third term in Congress, said he expected to be an underdog in what is likely to be a hotly contested Democratic primary. The race could also draw Angela Alsobrooks, the Prince George’s County executive who is seen as a rising star in the state, and Representative Jamie Raskin, the top Democrat on the Oversight Committee who has established a national following, having served as the lead impeachment manager prosecuting former President Donald J. Trump after the Jan. 6, 2021, attack on the Capitol. Will Jawando, a member of the Montgomery County Council, has already announced he is running for the seat.
“I’ll be the underdog in the race. I’m always an underdog. I’m a disrupter,” Mr. Trone said. “We take no money from PACs. I take no money from lobbyists, no money from corporations. And when you don’t take anybody else’s money, and you’re willing to put some of your own resources into the campaign, people realize you’re in it because you care.”
Those close to Mr. Trone said he was willing to spend tens of millions of dollars on the race, as he has in previous campaigns for the House.
In the House, Mr. Trone co-founded the Bipartisan Addiction and Mental Health Task Force, and he said he would focus on similar issues if elected to the Senate. He emphasized the need to address the opioid crisis, mental health issues and criminal justice reform.
Mr. Trone said he believed Maryland Democrats would choose a progressive candidate over any centrists who might enter the race, and that he believed his platform would appeal to liberal voters.
“We’re all on the same team,” Mr. Trone said of the other Democrats who are likely to run. “We despise the most narcissistic president, probably the worst president ever, Donald Trump.”
Mr. Cardin said in an interview that he did not intend to endorse a successor.
“We have a great group of Democrats in Maryland,” he said. “I know some are interested. I’m very confident that we will be able to to elect a Democrat to fill the seat.”
Whoever wins the Democratic primary is likely to carry the seat. The state’s most popular Republican, former Governor Larry Hogan, has said he is not interested in running.
Maryland’s filing deadline is Feb. 9, 2024. The primary election is May 14, 2024.