A longtime New Jersey state senator is leaving the Republican party to join the Democrats.

Samuel Thompson, 87, is running for re-election as a Democrat after the GOP took the side of his primary challenger.

New Jersey Republican defects

Thompson was upset when the GOP leadership encouraged him to retire and threw its support behind Thompson’s primary challenger, Old Bridge Mayor Owen Henry.

Thompson says the party “abandoned” him because of his age.

“The betrayal by so many of my friends — that was too much for me,” he said. “I am not leaving my party. My party leadership has left me.”

Thompson says he’s still vigorous enough to perform his role, which he described as a full-time commitment.

“It is my life. It gives me something to do every day when I wake up to get there and help people. The alternative is sit at home and just wait to die? I have to be active,” he said. “I think I’m doing a public service.”

"Unilateral decision"

The switch gives Democrats 25 seats in the 40-member state senate.

Thompson, who is currently in his fourth term as a state senator, began serving in the state assembly in 1998.

He said party leaders "wouldn't let me say goodbye to my friends that I served with for many years,” but Senate Minority Leader Steve Oroho (R) said that Thompson "made a unilateral decision to switch parties without talking to anyone from either side."

"He didn't seem to understand that it was inappropriate for him to try to join us after he announced he had become a Democrat," Oroho said.

Still supporting Trump

Thompson was a delegate for President Trump twice, and although he’s joining the Dems, he says he is still supporting Trump in 2024.

Despite his conservative leanings, Thompson said the Democrats had no issue with him joining the party.

"The Democratic Party has always been a big tent party and I welcome Senator Thompson to our ranks," Governor Phil Murphy (D) said.

All 120 seats in both houses of the state legislature are on the ballot this year. Thompson could be in for a tough fight in the Republican-leaning 12th district, which includes parts of Burlington, Middlesex, Monmouth and Ocean counties.