One underappreciated benefit of the New York City subway system is that it’s there when you just want to disappear. It can whisk you between boroughs with relative quickness. Even with recent Wi-Fi service installations, there are plenty of dead spots to blame for lack of contact. Sorry to miss your call, I was underground.

It was in this spirit, maybe, that Mayor Bill de Blasio added a last-minute event to his public schedule and hopped on an A train on Monday. Above ground, he’s got a healthy lead in the polls one week before Election Day, but a corruption trial going on downtown is generating awkward questions for the mayor, even though he’s not directly involved. The trial is for former correction officers’ union head Norman Seabrook, who has been charged with playing fast and loose with his union’s pensions in exchange for cash in a Ferragamo bag. But the government’s star witness is one Jona Rechnitz, who was once a big donor to de Blasio. And since taking the witness stand last week Rechnitz has been saying that the money helped him get access to the mayor, harkening back to an issue the mayor has tried hard to put behind him.

Who wouldn’t want to escape such headlines and lose oneself in the subway’s charms and aggravations? Monday morning de Blasio swiped into the 34th Street station, and like other inexperienced straphangers before him he took a friend along for company. That friend was Vermont Sen. Bernie Sanders.

Swipe in and keep moving

If the point was to kill some time, then things started out well for the twin progressives: they had a while to wait on the platform because, as usual, there was “an earlier incident.” So the mayor and the senator stood together and made small talk and listened to a couple of buskers busking: “Be the change you want to see in the world,” the singers sang.

With Sanders in tow, de Blasio had a big draw among his people. No real complaints about municipal issues when a national figure was steps away.

“We love you, Bernie,” people shouted, exhibiting a common affection on display Monday despite New York’s substantial support for Sanders’ 2016 opponent, Hillary Clinton.

“You should take the A train more often,” de Blasio joked as the train carried them downtown.

Rather than fielding questions about the Rechnitz testimony or other embarrassments, de Blasio and Sanders talked with a nearby rider about sports and NYC high schools.

“Lincoln was pretty good for a while,” the rider said. “Stephon Marbury went there.”

“No kidding,” Sanders said.

This was all a lot better than being forced to revisit the federal and state investigations into the mayor’s non-profit and campaign fundraising that ended without charges in the spring. The acting U.S. attorney noted at the time that de Blasio had “made or directed inquiries to relevant city agencies” on behalf of donors, a bit of a backhanded admonishment. Yet de Blasio seemed able to put the moment behind him and has repeatedly said that donors don’t get special treatment. Even a crowded train ride was better than another return to all that.

Before they exited, someone else shouted, “Keep speaking the truth” to Sanders. De Blasio concurred.

“It’s the only thing he knows how to do,” he said of his new friend, who he did not endorse for president.

Stand clear of the closing doors

Then they arrived at Fulton Street, where de Blasio talked about his plan to fund the beleaguered MTA: a small tax on city millionaires which would need approval at the state level. The state legislature has showed little appetite for the idea. Sanders, who also has no jurisdiction over the New York State Senate, nevertheless lent his bully pulpit in support.

“This is the wealthiest city in the history of the world,” he said.

The friendly tenor of their subway ride continued. Sanders called de Blasio “one of the great progressive leaders” in the country, and said the mayor “must be re-elected.”

Then the mayor gave what may be his best pitch for re-election, as well as his philosophy of incremental progressive governance. Yes, it may be tough to get a millionaires tax through a Republican-controlled State Senate, but here’s how you move forward: “Someone starts the ball rolling.”

You chip away until you get what you’re looking for: “That’s how change happens.”

So it was a successful escape to a safe subject-matter for de Blasio, but then the cynical NYC press corps dragged him back to the issues above ground. De Blasio’s opponents in the mayoral race spent the day harping on the Rechnitz testimony, rehashing the old accusations that de Blasio had successfully but temporarily avoided.

What did tribune Sanders think about endorsing a mayor who seemed to lend his ear, at least on occasion, to wealthy donors?

Sanders had no comment on that one and merely beckoned de Blasio forward to, once again, defend himself.

Even subway rides must end.