WASHINGTON — Sen. Bernie Sanders endorsed Cook County Commissioner Jesús “Chuy” Garcia for Congress on Thursday — giving a big boost to an important surrogate for his 2016 Democratic presidential bid and sending a message to potential primary rivals for the seat now held by Rep. Luis Gutierrez, D-Ill.

Sanders’ backing comes after Gutierrez anointed Garcia as his successor to represent the 4th Congressional District, which includes the most Hispanic parts of Chicago on the North and South sides.

Yes, Gutierrez has engineered things to make it highly likely that Garcia will emerge as the Democratic candidate after the March primary. That will be tantamount to election in this heavily Democratic district.

But it was not done to do a favor for Mayor Rahm Emanuel. More on that below.

Garcia’s wing of the Democratic Party helped Sanders, the Vermont Independent, come close to beating Hillary Clinton in the March 2016 Illinois presidential primary — in part by attacking Emanuel.

Garcia went on to become a key Sanders’ surrogate targeting Hispanic voters, traveling to key states during the campaign.

Sanders has kept his political movement alive with the creation of his “Our Revolution” nonprofit. The leaders of Our Revolution Illinois in Chicago include Garcia and Cook County Clerk David Orr. The chair is Clem Balanoff, who led Sanders’ Illinois presidential drive.

The seat has a history.

This incredibly gerrymandered “C” or earmuff shaped 4th District was created in 1992 to comply with the Voting Rights Act of 1965. The idea was to consolidate Hispanic voting strength by linking the North Side largely Puerto Rican neighborhoods with the Mexican-American communities on the South Side.

Gutierrez became the first Hispanic House member from Illinois, holding that seat since its inception.

Why Sanders endorsement is a big deal for Garcia in a Democratic primary:

• Sanders resonates with the non-Hispanic parts of the district — the hipsters and millennials and traditional liberals and progressive in the city.

• The district also takes in Cicero and some other suburban territory as it snakes it way west all the way to the 294 Interstate. And in the suburbs, Sanders has influence among the newest generation of activist Democrats who are loosely banded together in the “Indivisible” movement born after the election of President Donald Trump.

• This gives Garcia a fundraising edge if Sanders asks his backers to donate to Garcia. It’s highly likely Sanders would, if needed, fly to Chicago to stump for Garcia.

• Garcia now has a ready-made Sanders national organization to bolster his House bid.

• Sanders’ backing of Garcia gives him standing outside Chicago political fishbowl.

“Chuy Garcia is the right person at the right time for the work we have ahead of us,” Sanders said in a statement.

“He is ready and willing to stand up and fight for the working families of Chicago and our nation and take on the powerful special interests who have far too much power over the economic and political life of our country. He is also an experienced legislator who has risen up the ladder of Chicago’s brawling politics. That makes him well groomed for jumping into the House’s rough and tumble political battles.” Sanders said.

ON THIS CRAZY STUFF ABOUT RAHM AND LUIS

Garcia forced Emanuel to a runoff in the 2015 mayoral race.

But this story line I’ve been hearing — that somehow Gutierrez decided to quit the House after 25 years to make it easier for Emanuel to win re-election in 2019 by getting Garcia out the way — is ridiculous.

If Garcia does end up in Congress, and it helps Emanuel, well, that is an unintentional and unavoidable byproduct. Neither Garcia nor Gutierrez care enough about Emanuel to make this switcheroo just for him.