In times not long past, last week’s news would have cinched it: Construction of the extended Green Line, better known as Southwest light-rail transit (LRT), would be assured. An accord struck by the Hennepin County Regional Railroad Authority and the Glencoe-based Twin Cities & Western Railroad (TC&W), which will share a corridor with Southwest, removed the last local impediment to the project. Long years of arduous procedures and perilous politics have produced arrangements that satisfy all of the requirements for federal funding.

In America B.T. — Before Trump — that would have sealed the deal. Federal funds would have soon and reliably begun to flow to cover the promised half of the $1.9 billion project’s construction costs. Construction would start this fall.

In America A.T. — After Trump — much has changed. Just how much has changed for Southwest LRT remains to be seen. But now would be a fine time for a visible show of support for the 14.5-mile project from one key Minnesota Republican in Washington: U.S. Rep. Erik Paulsen.

Why Paulsen? Because Southwest LRT’s route is partly in his district and will be a boon to many of his constituents. (The same can be said about the Orange Line bus rapid transit project, which is also awaiting federal funds.)

And because Paulsen is well-positioned politically to keep at bay those in the Trump administration or his party (and its fossil-fuel industry allies) who dislike mass transit and would like to derail Southwest. He’s the longest-serving Minnesota congressman in President Donald Trump’s Republican Party. He’s also in a tough re-election battle in which he is already emphasizing his independence from Trump.

Standing up for Southwest now would enhance that message. Paulsen could do so with political cover from the leading voices in the Republican-allied Minnesota business community, all of whom support Southwest for the boost it could give employers’ efforts to attract and retain workers.

A show of Republican support for Southwest is in order now because of mounting evidence of Trump administration hostility to transit, even in the face of action by a Republican-controlled Congress earlier this year to keep money flowing for new projects. That decision ran counter to Trump’s recommendation that funding for new projects cease.

A key Federal Transit Administration administrator sent a worrisome advisory letter late last month saying that the decision to fund new projects was “ultimately a discretionary one” for the administration. The lead Democratic members of Congress countered with a letter arguing that current law does not give the administration authority to choose which projects are deserving.

When a project meets the stated criteria in law — as Southwest does — it must be funded, Reps. Peter DeFazio and Eleanor Holmes Norton wrote. “We remind you that the president’s budget proposal is merely a request to Congress and provides the administration no legal authority to disregard current law,” they wrote.

That reminder would pack more punch if it came from a Republican like Paulsen. Now would be a fine time for Southwest LRT backers to encourage him to help bring a billion dollars of federal investment home to the Third District.