Of all the issues at stake as President Donald Trump and Democrats wrangle over his prized border wall, the latest snag is whether bargaining over the proposal should come before or after shuttered government agencies reopen.

It sounds like one of those perplexing snits that frustrates Americans and prompts them to blame both parties for Washington’s dysfunction. But it’s actually a consequential dispute about who’ll have leverage, now and later, as the partial shutdown enters its 27th day Thursday, setting a dubious record for duration.

If Trump blinks first and temporarily halts the shutdown so negotiators can seek agreement, the White House and some Republicans worry there’ll be no incentive pushing Democrats to cut a deal. With 800,000 federal employees back at work and getting paid, why would Democrats agree to provide billions in taxpayer money for a keystone of Trump’s presidential campaign that they hate and that he promised repeatedly Mexico would finance?

Yet Democrats fear that if they negotiate while the shutdown persists, it would encourage Trump to use such brinkmanship in the future. He’d think the pressure tactic had worked, and he’d have plenty of opportunities to do the same in the near future, they say.

Later this year, Congress and Trump will have to renew the government’s borrowing authority or face the first federal default, which many believe would batter the economy. By autumn, lawmakers will also need to approve a fresh round of spending bills for next year, providing opportunities for Trump to threaten a new shutdown for whatever issue he deems worth highlighting as his 2020 re-election campaign revs up.

The Democrats’ No. 2 Senate leader, Dick Durbin of Illinois, likened the situation to a family whose ornery uncle lives upstairs and threatens to turn off the electricity every time they talk about building an addition.

“You say to yourself, ‘Am I going to encourage him to shut off the electricity every time there’s a family discussion over an issue?’” Durbin said. “You’ve got to tell the uncle upstairs, ‘That’s unacceptable.’”

That same desire to maintain leverage is what’s helped keep many Republicans on Trump’s side.

Underscoring that, Sen. Mike Rounds, R-S.D., said Republicans were divided over a proposal by Sens. Lindsey Graham, R-S.C., and Chris Coons, D-Del., for a three-week respite from the shutdown while negotiators seek agreement on wall money. Trump has previously spurned the idea.

To strike a deal temporarily reopening government, the commitment from Democrats “would have to be pretty strong to get something done” on the wall, Rounds said. Otherwise, he added about Trump, “If it’s just seen as a weakening of his position, then he probably wouldn’t do it.”

Graham, who is close to Trump, has been among the most outspoken Republican advocates of temporarily halting the shutdown.

“If you open the government back for a defined period of time, you’ve lost nothing if you can’t reach a deal,” Graham said in an interview. “I haven’t had one Democrat come up to me and say, ‘Let’s do a deal with the government shut down.’ They’re all saying, ‘There’s something we can do, but we just can’t do it now. Why? Because if you do it now, they’ll shut down the government next year for something else.’ I share that sentiment.”

Trump is demanding $5.7 billion to build more than 200 miles of his proposed Southwest border wall, and has refused to sign spending bills reopening government lacking that money. Democrats say they won’t give him any wall funds but have been willing to provide $1.3 billion for other types of border security, like technology and some physical barriers.

Polls this month show more Americans blaming Trump than Democrats for the shutdown, a comfort to Democrats and a concern for a growing number of Senate Republicans including some seeking re-election in 2020 from swing states like Colorado and Maine.

But majorities of Republicans polled agree with Trump that there’s an immigration crisis at the Mexican border and blame Democrats for the shutdown. That means GOP senators abandon Trump at their own peril.

All this helps explain why Senate Majority Leader Mitch McConnell, R-Ky., has refused to force a solution to the standoff.

McConnell is known for brokering bipartisan agreements in the past. But ever since Trump walked away from a pre-Christmas deal to avert the shutdown that both parties thought the White House backed, McConnell has said it’s up to Trump and congressional Democrats to craft a compromise.

McConnell has ruled out sending legislation reopening the government to Trump for a certain veto. Some have mentioned that tactic as a way of letting vulnerable GOP senators demonstrate they want to end the shutdown, but many Republicans have no desire to defy Trump and risk retribution from the president’s loyal legion of voters.

“The number of people ready to end the shutdown is a pretty good-sized number,” said Sen. Roy Blunt, R-Mo., a member of his party’s Senate leadership. “But the number of people willing to take actions that they know the president doesn’t agree with and won’t be successful is a much smaller number, if that number exists at all.”