WASHINGTON — When first lady Michelle Obama hits the 2016 campaign trail for the first time on Friday, the test will be whether she can transfer her popularity to Hillary Clinton, who’s facing an increasingly tougher battle against Donald Trump.

She will go just a few miles from the White House for her initial event, to suburban Virginia, a battleground state President Barack Obama won in 2008 and 2012.

With Michelle Obama finally launched, the White House deployment for Clinton is complete. Obama, Vice President Joe Biden and the first lady are all enjoying high approval ratings and can vouch for Clinton, who suffers from a deep trust and credibility gap with voters.

I expect all of them at some point to come to Illinois to stump for Democratic Senate candidate Rep. Tammy Duckworth.

The president and Joe Biden have already been out for Clinton and have reserved days on their calendars to go on the road.

OPINION

A source familiar with Obama’s campaign travel said he will concentrate at this stage on the battlegrounds of Florida, Ohio, North Carolina and Pennsylvania and maybe expand to Iowa and New Hampshire.

With Friday marking 52 days until the election, Obama and Biden each will likely devote at least one day a week on campaign travel.

How much time Michelle Obama will devote to campaigning for Clinton and down-ticket contenders is still a work in progress. She is a reluctant campaigner, very careful about where she goes, and is a tough get.

“The president and first lady focus is on getting the Obama coalition out to the polls for Hillary Clinton,” Jennifer Psaki, the president’s communications director, told me. “That means engaging and energizing the African-American community, young people, and remind voters, including Independents, what’s at stake in November.”

Trump’s base includes angry white voters who feel nobody is looking out for them. Biden’s expertise is passionately relating to middle-class folks who have struggled. He has already been twice to the battlegrounds of Ohio and his native Pennsylvania. Biden and Clinton, whose father was born in Scranton, visited Biden’s childhood Scranton home together last month.

Biden and Clinton breakfasted together once a week at his vice presidential residence when she was Secretary of State. “One of the added values he brings to this campaign is that he knows Hillary Clinton so well,” Biden’s communications director, Kate Bedingfield, told me.

Obama has created a valuable brand for herself since she moved into the White House, nurtured all these years by being very judicious in her choice of public events and interviews.

Indeed, on Friday morning, before heading to Fairfax, Virginia, for the Democratic Party of Virginia rally for Clinton, she will join former first lady Laura Bush at the National Archives for a “conversation” about the programs they launched to help military families.

“The First Lady is looking forward to campaigning this fall for Hillary Clinton and Tim Kaine, starting with the event in Northern Virginia,” said her communications director, Caroline Adler Morales.

“Her focus will be on urging voters in key swing states, especially young people and African Americans, to register to vote, and be sure to cast their vote in November. The First Lady’s remarks supporting Sec. Clinton will be focused on the qualifications and demeanor a President needs, the values we hold dear as Americans, and our shared hopes for the future,” Morales said.

Michelle Obama is adept at social media and is a total ham. Two recent hits: Hilarious videos with Ellen DeGeneres, who takes her shopping at a CVS to ready her for post-presidential life, and singing in James Corden’s “Carpool Karaoke.” I’m told she also will be using other platforms to reach voters.

Clinton campaign chair John Podesta told me: “We can use her in every state that’s competitive. She’s extremely popular. She was great at the convention. She is an amazing and helpful surrogate for Hillary.”