Sen. Branden Petersen, R-Andover, who was elected to the House in 2010 at the age of 24 and to the Senate in 2012, announced Monday he will not seek another term in 2016, citing family and financial obligations.

Petersen, who was a co-sponsor and the sole Republican senator to vote for the measure legalizing gay marriage in 2013, is not going quietly. Although he will leave with a strongly conservative voting record, Petersen said the Legislature needs a broader, more diverse array of citizen legislators and more lawmakers willing to question perceived dogma, be it in the Legislature or in their own party.

“When the rubber meets the road, group psychology is pretty powerful and plays itself out in ways that I don’t think always serve the interests of the constituents,” he said in an interview Monday.

But Petersen said his reasons for leaving were mostly closer to home: Family and finances.

He has three young children, ages 4, 3 and 11 months.

The Legislature “consumes a lot of mind-share all of the time. I’d like to be more present for my family,” he said.

Petersen also said he is entering his prime earning years, and has not found it easy to secure the kind of job that would give him several months a year to legislate. He currently sells cars at an Elk River dealership.

He said he’s not the only legislator to deal with this problem. The result, he said, is a shallow pool of candidates and lawmakers who often are independently wealthy, lawyers or public employees whose collective-bargaining agreements guarantee them the ability to serve.

“If you want to have a more diverse group of legislators, people who do different things, with different age groups and representing different parts of the population, you need to pay more or go to a shorter session,” he said.

Legislators are paid $31,140 per year plus a modest stipend for living expenses during the legislative session.

Petersen, who once was admonished by local Republicans over his support for gay marriage, said he expected a Republican primary challenge next year, but he said he would have prevailed had he decided to run again.

Petersen joins Sen. Julianne Ortman, R-Chanhassen, and Sen. David Brown, R-Becker, in not seeking re-election.

Republicans have high hopes to take the upper chamber, given a number of DFL senators from districts that lean Republican.

Sen. Scott Dibble, DFL-Minneapolis, a leader in the gay marriage fight, praised Petersen on Twitter: “It’s not going to be the same, brother and friend. You made a huge difference for the better.”

Petersen said a return to politics is possible, and that he will continue to be outspoken on matters of public interest.