Hartford — Since state Sen. Edith Prague, D-Columbia, announced Tuesday that she won't seek re-election this fall, the field of candidates to succeed her has continued to grow.

On Thursday, state Reps. Chris Coutu, R-Norwich, and Tom Reynolds, D-Ledyard, both confirmed they are now officially in the race. They join Sprague First Selectman Cathy Osten, a Democrat, who revealed her ambitions on Wednesday.

For Coutu, the jump into the race meant abandoning an uphill campaign to unseat U.S. Rep. Joe Courtney, D-2nd District. Coutu said his decision to go for state Senate was based on what's best for his young family as well as practical considerations. Taking on Courtney "was David versus Goliath," he said.

The reaction to his switch has been positive and supportive, he said. He plans to return the roughly $60,000 in contributions that his congressional campaign has on hand, he said.

Reynolds, a deputy majority leader in the House, said he felt he is the strongest Democrat in the field and the party's best shot to retain Prague's seat.

As his House district leans Republican, Reynolds said, he has experience winning votes from a broad swath of the electorate.

"I don't believe in shopping for offices," he said. "The voters need to know that someone is firmly committed to the role they are pursuing, and not simply making decisions based on what serves the changing self-interest of candidates."

The Democratic State Senate Convention is scheduled for May 21 in Norwich.

"Every two years, I pose the same questions, 'Am I making a difference?' And, 'Where can I best serve the region?'" Reynolds said. "In thinking about those questions, I concluded that the state Senate is the best platform for me to continue to advance what have always been my priorities, which are building Connecticut's economy to create jobs, reforming public education, supporting working families and reforming government."

Osten, a retired state correctional lieutenant, said her experience running a municipality has made her attuned to the issues facing towns and their residents.

She also enjoys strong union support. For two years, Osten was president of the nearly 4,000-member state employees union CSEA/SEIU Local 2001. Prague, who first won the Senate seat in 1994, praised Osten's labor background this week as she pledged to endorse her.

"I don't think I could get a better endorsement from anybody," Osten said. "I see myself as having similar concerns as Senator Prague, with seniors and middle-class folks and just workers in general, and I think I would be a great advocate for her constituents."

Coutu, who out polled Osten by nearly 15 percent in her 2010 challenge to his House seat, said he believes he can appeal to the senior citizens who strongly supported Prague through his record of looking out for taxpayers' interests.

"I've learned through many seniors the challenges they have with constant tax increases, utility rate increases, gas tax increases," Coutu said. "I will be an advocate to make sure we don't raise the taxes that hurt them."

For her part, Osten said her election loss two years ago is irrelevant to this year's race.

"This is a completely different district," Osten said. "Chris is not an incumbent, and it's an open seat."

Coutu's withdrawal from the 2nd Congressional District race leaves Daria Novak of Madison the GOP frontrunner to face Courtney. "I called her and wished her the best," he said.

Of the state Senate's 36 members, 22 are Democrats and 14 are Republicans.

j.reindl@theday.com