Can’t deal. Photo: Saul Loeb/AFP/Getty Images

“The worst thing you can possibly do in a deal is seem desperate to make it,” Donald Trump once paid someone to write. “That makes the other guy smell blood, and then you’re dead.”

If his nostrils aren’t clogged, Chuck Schumer should be getting a big whiff of vital fluid right about now.

With the government set to run out of funds at the end of next week, congressional leaders were making steady progress toward a new, bipartisan spending bill — when the White House barged into negotiations with a list of weighty demands.

Specifically, President Trump is demanding billions in funding for a border wall, immigration enforcement, and the military. Democrats have already declared wall funding a nonstarter — and Republicans will need Team Blue’s votes to overcome the reflexive opposition of the tea-party hard-liners in the House and the filibuster in the Senate.

But the White House is insisting on its wall, nonetheless. And in a flood of leaks to major news outlets, the administration has signaled that its demands are nonnegotiable — because Trump is worried he’ll receive bad media coverage if he doesn’t fulfill more campaign promises by April 29, the 100th day of his presidency.

By the way, few are talking about this one other big problem the wall would cause.

The president is so preoccupied by the fear of such bad press, he’s already preemptively defending himself against it on social media.

No matter how much I accomplish during the ridiculous standard of the first 100 days, & it has been a lot (including S.C.), media will kill! — Donald J. Trump (@realDonaldTrump) April 21, 2017

To be fair, the 100-day milestone is arbitrary. But it’s also the deadline Trump set for himself in his “Contract with the American Voter.”

Last year, Trump released a Contract With The American Voter, outlining an agenda for the first 100 days. Here's the status of that agenda: pic.twitter.com/cujdxe30OT — Matt McDermott (@mattmfm) April 18, 2017

It makes sense, then, that the White House would want a victory on its “big, beautiful wall” (and, if possible, its hideous health-care bill) by the end of next week. But why Trump thinks he can force Democrats to hand him that win is harder to understand.

Trump has informed Democrats that he is deeply concerned about the optics of his 100th day. He has then ordered them to vote for his monument to American xenophobia — or else, he will force the government to shut down … on the morning of his 100th day.

If Trump dreads the prospect of having no major legislative accomplishments to tout by day 100, then he must be horrified by the idea of the government literally ceasing to function the moment he hits that milestone.

As Republicans well know, public anger over government dysfunction tends to fall hardest on the president and his party. Trump has the most to lose of any player in these negotiations — and he’s gone out of his way to make sure his adversaries are aware of that fact.

And Democrats are using their leverage. Right now, the donkey party isn’t just telling Republicans what can’t be in the spending bill, but also what must be in it. Nancy Pelosi and Chuck Schumer have signaled that permanent funding for Obamacare’s cost-sharing subsidies will be the price of Democratic cooperation. A federal judge has ruled that those subsidies require a new congressional appropriation. But the Executive branch is allowed to continue providing them, so long as it proceeds with an appeal of that judge’s decision. This means that Trump could unilaterally gut Obamacare in a heartbeat, simply by withdrawing the government’s appeal. And, in recent weeks, the president has threatened to do just that.

At this point, Congress’s best option is probably to buy more time for negotiations, by passing a continuing resolution to keep the government funded for an additional week or two. After that, their best bet may be a bipartisan deal in which Democrats agree to spending increases for immigration enforcement and the military in exchange for permanent funding for those Obamacare subsidies.

Of course, that would require the president to give up his beloved wall and precious hostage. But as every artful dealer knows, that’s what happens when you let the other guy smell your blood.