California Lt. Gov. Gavin Newsom says he will start raising money to run for governor in 2018

California Lt. Gov. Gavin Newsom, who gained national attention as mayor of San Francisco for ordering then-illegal gay marriage licenses to be issued, said Wednesday that he will begin raising money to run for governor in 2018, a position he has long sought.

The announcement from the 47-year-old Democrat comes just a few months after he was re-elected to a second four-year term as the state's second-highest elected official. Newsom said last month that he would not pursue a U.S. Senate seat, creating anticipation he would seek the state's top post.

The former mayor of San Francisco has been a controversial national figure since 2004 when he ordered the San Francisco city clerk to ignore state law at the time and issue marriage licenses to gay couples. Newsom served eight years as mayor.

In a written announcement Wednesday, Newsom said he passionately believes "in the future of this great state." He said that although California has reigned in its finances, it still faces daunting long-term challenges in creating private-sector jobs, investing in public education and keeping college affordable.

"The reality of running for governor — even four years from now — in America's largest, most diverse state demands that I start raising resources now if we're going to lead a conversation worthy of the 38 million people who live, work, attend school and raise families in the Golden State," he said.

Newsom launched a brief campaign for governor before dropping out in 2009 as then-Attorney General Jerry Brown sought the position. Brown won in 2010 and was re-elected in November.

Although Newsom praised Brown in his announcement Wednesday, the two are not known to be close, despite a longstanding relationship between their families. As governor from 1975 to 1983, Brown appointed Newsom's father as a superior court judge and later to the state Court of Appeals.

Newsom last year became the highest-ranking Democrat to challenge Brown's $68 billion high-speed rail project, saying he no longer backs the bullet train and would like to see the money diverted to more pressing infrastructure needs.

He has more than $3 million remaining in his campaign for lieutenant governor after cruising to re-election in November.