Welch's decision comes a week after the 81-year-old Leahy's announcement that he will not seek reelection to the seat he first won in 1974.
The 74-year-old Welch said the 2022 election will determine control of the Senate and, with it, what he can accomplish for Vermont families.
“We are at a pivotal moment,” Welch said in a statement distributed by his campaign. “Vermont families are struggling through multiple crises: a global pandemic, the consequences of climate change, and a racial reckoning generations in the making."
He said that if elected he would be ready to fight for progressive change from the first day in office.
He promised to continue to fight to ensure working families have access to child care and paid family leave. He said he also would work to pass a Green New Deal to protect the environment, lower the cost of health care and prescription drug costs, ensure that women have control over their own health care decisions and protect voting rights and American democracy.
The decisions by Leahy and now Welch will create the first open seats in Vermont's three-member congressional delegation since 2006, when independent Bernie Sanders moved to the Senate and Welch took his seat in the House.
While the Senate seat will be open, Welch, who during his years in the House has been consistently one of Vermont's top vote-getters, would have an instant advantage.
Vermont's popular Republican governor, Phil Scott, has said he is not interested in running for the Senate. It's unclear whom the state GOP will find to run for either the Senate seat or the House seat.
Vermont has never sent a woman or a member of a racial minority community to Washington. Several female politicians have expressed interest in running for a vacant seat, but the only person who has said she would run for the House if Welch ran for the Senate is Democratic state Sen. Kesha Ram Hinsdale.
Welch, of Norwich, was first elected to the U.S. House in 2006.
During his years in the House, he has worked for energy efficiency, cutting the prices of prescription drugs, investing in infrastructure and expanding broadband into rural areas of Vermont and the country.
As of this year, Welch served as a chief deputy whip of the House Democratic Caucus and a member of the Democratic Steering and Policy Committee.
In the House, he has served on the Permanent Select Committee on Intelligence, the Committee on Energy and Commerce and the Committee on Oversight and Reform.
Welch has developed a spot for himself in the House and is well liked there, said Linda Fowler, professor emerita of government at Dartmouth College.
Welch was born in Springfield, Massachusetts. He moved to Vermont in the early 1970s after graduating from law school. He served as a public defender and founded his own law firm.
He was elected to the Vermont Senate in 1980 and became the first Democrat elected as Senate president pro tempore in 1985. He was reelected to the state Senate in 2002 and served in that role until he was was elected to the House four years later.
Welch said even though the country is facing extreme challenges he is optimistic.
“I’ve seen Vermonters come together to solve problems," he said. "We focus on solutions, not who gets credit. That’s the Vermont way. That’s how I’ve gotten things done as Vermont’s congressman and how I will get things done if I am elected to the U.S. Senate.”
Lisa Rathke And Wilson Ring, The Associated Press