Former U.S. Sen. Lincoln Chafee said he's highly likely to make a Democratic primary challenge to Sen. Sheldon Whitehouse this year.
"I'm 90 percent there," Chafee told Rhode Island Public Radio, adding that he has not made a final decision.
Chafee, 65, said supporters of U.S. Sen. Bernie Sanders of Vermont, who ran for president as a Democrat in 2016, approached him months ago and encouraged him to run for the Senate.
"I care deeply about these issues, and Senator Whitehouse voted against a Sanders resolution -- Sanders and Mike Lee from Utah, Republican from Utah, resolution not to extend war powers to President Trump and Senator Whitehouse did not vote for that. They got 44 votes."
Chafee was appointed by Gov. Lincoln Almond to fill the remainder of his father's term after John Chafee, an icon of GOP moderation, died in 1999. Chafee won the seat in 2000, but lost it to Whitehouse in 2006 largely due to the unpopularity in Rhode Island of President George W. Bush.
The former senator and Warwick mayor won election as governor as an independent in 2010, later switched to become a Democrat, decided against seeking re-election in 2014, and then made what was largely viewed as a quixotic presidential run in 2016.
Chafee flirted with a run for governor this year, but increasingly downplayed his interest in that race.
Chafee pushed back at the suggestion that he's persisting in politics when his time and effort might be better spent elsewhere.
"I've won 10 races in Rhode Island, and they'll all been competitive and I believe I've been outspent in all of them," he said. "So I know how to win elections and I have a record of winning elections and I think I'm going to win this one."
Chafee noted how Whitehouse, an outspoken environmentalist, has not taken a stance on the controversial proposed for a gas-fired power plant in Burrillville. "That's a big issue in Rhode Island," he said, not taking a stance is "inconsistent with his speeches on climate change."
The Democratic Senatorial Campaign Committee is now led by Mindy Myers, a former chief of staff for Whitehouse who piloted his winning campaign over Chafee in 2006.
In a statement, Whitehouse said, "I look forward to spending the months ahead talking with the people of Rhode Island about how I'm fighting every day in the Senate to grow the middle class, protect health care, and leave our planet a better place for the next generation. I welcome any and all Rhode Islanders to take part in that conversation."
Two Republicans, former state Supreme Court judge Robert Flanders and state Rep. Robert Nardolillo, are vying to take on Whitehouse.
Chafee also pointed to how Whitehouse backed Hillary Clinton at the Democratic National Convention in 2016, despite how Sanders won Rhode Island's Democratic primary that year. Chafee said he believes Sanders would have defeated Donald Trump in the presidential race. "There was tremendous thirst for an outsider," Chafee said.
This post has been updated.