Lt. Gov. Timothy Murray, after spending the last 15 years in local and statewide public office, will not run for governor in 2014, citing the time commitment that would be required to juggle his current job, a full-time campaign, and his responsibilities to his family.

“As I contemplate the commitment required over the next 20 months (and the following four years as Governor) and weigh that against my obligations and responsibilities to my young family, I have decided that I will not be a candidate for Governor in the 2014 election cycle. Nor will I be a candidate for any other statewide office in 2014,” Murray said in a letter to supporters emailed out Friday morning.

Murray, who rose from a city councilor and mayor in Worcester to win two statewide elections and serve as lieutenant governor for the past six years, has been Gov. Deval Patrick’s righthand man since 2007, a constant supporter and the administration’s key liaison to cities and towns.

Over the past several months, Murray has ramped up his fundraising efforts, raising more campaign cash than any other statewide elected official in 2012 and building an account that many considered a prelude to his eventual run for governor next year. At a speech to the Greater Boston Chamber of Commerce in November, Murray said, “I would like to be governor,” but qualified that by staying he still had not made a decision to run.

Murray, however, said the political efforts of the past several months and his experience running two statewide campaigns gave him a taste of what it would be like for the next six years, should he win, campaigning mornings, nights and weekends while also performing his duties as lieutenant governor and being there for his family.

“This activity already adds to a busy schedule with more morning, evening and weekend events quickly filling almost every free moment,” Murray wrote. “Looking forward, I have given considerable thought on how I can sustain this pace for the next 20 months while working on my portfolio of issues as Lieutenant Governor. More importantly, I have been grappling with how I can juggle a campaign and work duties with my responsibilities as a husband and the father of two active and beautiful daughters, Helen and Kati, who are 7 and 6 years old.”

Murray has remained a popular political figure with mayors and city councilors around the state, but his political brand has suffered over the past year following an early morning car crash in Sterling, and questions about his political ties to disgraced former Chelsea housing director Michael McLaughlin.

In his letter, Murray does not allude to either of those hurdles to a successful gubernatorial campaign, talking only about his appetite to commit to the time and energy it would take to campaign.

Murray says in the letter that he was anticipating both a primary and general election contest, with Democrats like Treasurer Steven Grossman and state Sen. Daniel Wolf publicly considering running for governor in 2014. Dr. Donald Berwick, a pediatrician and former head of the Centers for Medicare and Medicaid under President Obama, also came to visit Murray over a week ago to let him know he was considering running.