WASHINGTON — In the hours leading up to the federal government shutdown, a common refrain was heard from both Democrats and Republicans: President Trump, who campaigned as a master negotiator, needed to take the lead and bring both sides together to strike a deal.

But by yesterday, after the White House again torpedoed the prospect of a deal to keep the lights on in federal offices, many Democrats and Republicans sang a different tune: The president should stay out of it.

Trump simply cannot be trusted, they said.

“We cannot get a straight answer from this White House,” said Sen. Jeff Flake (R-Ariz.), who stressed lawmakers cannot wait for assurances of Trump’s support.

Sen. Patrick Leahy (D-Vt.) wondered how, even if lawmakers negotiated with Trump in good faith, they could take Trump’s word “when we know he is only one tweet away from changing his mind?”

Lawmakers’ skepticism of Trump’s word is warranted. In the weeks leading up to the shutdown, Trump repeatedly acted like Lucy van Pelt, holding out his support of a potential deal like a football — only to yank it away at the last moment and leave lawmakers flat on their backs like Charlie Brown.

The latest episode happened hours before a shutdown, when he and Senate Minority Leader Chuck Schumer (D-N.Y.) came up with an outline of a potential agreement yesterday afternoon — with Schumer even agreeing to significant funding for Trump’s demanded southern border wall. But by evening the White House had nixed the idea.

Schumer, who has had a front seat to Trump’s roller coaster style of negotiating, said yesterday he believes the president wants to get to a deal done. The problem, he said, is the group of immigration hardliners in the ear of the mercurial leader.

“Negotiating with this White House is like negotiating with Jell-O — it’s next to impossible,” Schumer said, suggesting that Trump’s own wishes are frequently derailed by immigration hard-liners like chief of staff John Kelly, senior adviser Stephen Miller or GOP Sen. Tom Cotton of Arkansas.

“As soon as you take one step forward, the hard right forces the president three steps back,” he said.

And Trump’s tweets aren’t helping.

“Democrats are holding our Military hostage over their desire to have unchecked illegal immigration,” he tweeted yesterday, further fraying trust between the parties.

For a self-proclaimed master deal maker, that’s not exactly a way to bring parties to the table.

But without good faith, few still believe a seat at that table is worth it.