ALBANY, N.Y. (AP) — New York Gov. Andrew Cuomo will need a new running mate, after Lt. Gov. Robert Duffy announced he would not seek another term, less than two weeks before Democrats gather to nominate their candidates for the fall elections.

Duffy, the former mayor of Rochester, informed Cuomo of his intentions in a letter dated Wednesday. The departure leaves Cuomo without one of his strongest political links to the upstate but creates an opportunity to reshuffle the ticket as he prepares to formally launch his bid for a second term.

The 59-year-old Duffy said that while he is proud of the administration's work, the job's travel demands were causing "constant back and leg pain." Duffy said he also wants to spend more time with his family. He said he made the decision with "mixed emotions."

"I have often traveled thousands of miles weekly because of the importance of being on the ground and reaching out to our constituents," he wrote in the letter, first reported by the Democrat and Chronicle newspaper.

Cuomo praised Duffy's service, noting he rose from being a police officer to Rochester's chief of police to mayor.

"Few people have traveled more miles, heard from more New Yorkers, or had a greater impact on this state than Bob Duffy," the governor said.

Cuomo is widely expected to tap a running mate from western New York or Long Island — both considered political tossups. Buffalo Mayor Byron Brown, Suffolk County Executive Steve Bellone and former U.S. Rep. Kathy Hochul of Buffalo have been mentioned as possibilities.

An announcement is expected soon. Cuomo's office declined to offer a timetable for a decision on a running mate.

Gerald Benjamin, a political science professor and dean of the College of Liberal Arts and Sciences at SUNY New Paltz, noted that like Cuomo, the other prominent Democrats seeking re-election — Attorney General Eric Schneiderman and Comptroller Thomas DiNapoli — are white men from downstate. He predicted that Cuomo would look for a candidate who is a minority, a woman or from upstate.

"There's the classic issue of downstate dominance in state politics," Benjamin said. "The theme here has to be political balance as a priority."

Duffy said he planned to campaign for Cuomo and his running mate, and that he considered the governor a friend. He cited the successful passage of gay marriage, the administration's response to Superstorm Sandy and its focus on fiscal restraint and economic development as highlights of their work together.

"As you and I discussed many times, upstate New York was all but abandoned by past administrations and downstate received much of the focus," he wrote. "We have remedied that and upstate New York has received unprecedented focus and resources and has responded with growth unseen in many years."

The former police officer-turned-politician said he will serve out the remainder of his term and has no plans to seek another elected office. Duffy purchased a lakefront home in the Finger Lakes last year and wrote in his letter that he plans to spend the rest of his life in the region.