PORTLAND — On a wet patio above a bustling diner, Maine Gov. Paul LePage on Wednesday morning became the first Republican governor in the nation to endorse a presidential candidate for 2016: Gov. Chris Christie of New Jersey.

LePage described Christie as a mentor and a friend and thanked him for his support during a tough re-election fight in Maine last year, when as head of the Republican Governor’s Association Christie came to Maine four times to stump and raise funds for LePage.

Those stops included one at Becky’s Diner, where the duo returned Wednesday.

“When all of you and your colleagues around the country had me as a dead-walking governor, Chris Christie had faith. He believed in us, came up, supported me wholeheartedly, never batted an eye,” LePage told a gaggle of local and national reporters in attendance.

“I think he’s the real deal,” LePage later added. “He’s been a governor. He knows what hard decisions are. He’s going to make them. He’s not going to be a politician and talk out of both sides of his mouth. He’s going to tell you things you may not want to hear, but you need to. Then he’s going to go to work trying to fix them.”

Wednesday marked Christie’s first full day as a 2016 Republican presidential candidate. Portland was his first stop before traveling to New Hampshire, site of the nation’s first presidential primaries, for a schedule packed with public and private events through Independence Day weekend.

Christie said he was honored to have LePage’s endorsement because he and LePage are cut from the same cloth — no-nonsense conservatives elected to run largely Democratic states.

“He’s one of those guys who people really know and believe and understand,” Christie said of LePage. “That’s why for me, in the first full day of my presidential campaign, to be able to come up here and receive an endorsement from somebody who knows what it’s like to run a blue state, knows what it’s like to make tough decisions, knows what it’s like to engage in hand-to-hand combat to try to get things done for the people that elect you, to get an endorsement from Paul LePage today is an incredible honor for me.”

Christie and LePage first met in 2010 and said they and their families have been friends ever since. According to campaign finance reports, the RGA under Christie’s watch spent $5.1 million to help re-elect LePage in 2014, the most spent by any group on any candidate in 2014.

LePage’s backing could help Christie win over conservative voters, a powerful force in primary elections. Christie’s occasional bipartisanship in Democrat-leaning New Jersey, such as his decision to expand Medicaid in his state, a key pillar in Democratic President Barack Obama’s health reform law, has earned him scorn from conservatives in the past.

Christie, who like LePage is known for a brash style adored by supporters and scorned by opponents, once was viewed as a front-runner for his party’s nomination in 2016.

That status has been diminished, partly because of the entrance of high-profile Republicans such as former Florida Gov. Jeb Bush into the race, and the “Bridgegate” scandal of 2013, when Christie aides orchestrated the closing of approach lanes for the George Washington Bridge connecting New Jersey and New York City, the busiest bridge in the country.

Critics said the closings were political retribution against a Democratic New Jersey mayor, who turned down a request that he endorse Christie’s re-election campaign. Christie has disavowed knowledge of the closures and a federal judge in New Jersey on Monday dismissed a class-action lawsuit filed by people stuck in traffic in the bridge lane closings.