President Donald Trump wants to negotiate a deal over border security before reopening the government. Congressional Democrats, many of whom support tougher border security measures and some of whom even support a bigger, more extensive wall on the southern border, won't negotiate with Trump on border security until the government reopens.

He's mostly wrong, they're mostly right.

Congress and the president have fought over specific spending projects (often in the Defense Department budget) multiple times over the years, and sometimes those fights have resulted in the lights going out in parts of the federal government. That's the inevitable result of a Constitution that gives Congress exclusive power to appropriate but the president the power to veto appropriations bills.

The issue here is how much of the government should be paralyzed by this fight. Nine departments and dozens of agencies have been idled – they were the ones clumped together in a temporary funding bill that elapsed Dec. 21. Their workers and contractors have gone more than a month without pay, the economy more than a month without their spending, and the public more than a month without their services.

Democrats want to fund eight of those departments and most of the agencies through the end of the fiscal year, while providing temporary funding to the Department of Homeland Security – the one in charge of border security – to keep the pressure on lawmakers to hammer out a deal with Trump on the wall.

That's not just reasonable, it's the only approach that makes sense for Congress in the long run – for the sake of their institution, not just government employees, contractors and taxpayers. If presidents are allowed to take agencies hostage when their funding is not in dispute, then the president will have an incentive – and leverage – to use spending bills continually to extract concessions on ... anything.

It doesn't take much imagination to see where this could lead (A shutdown over single payer! Or universal background checks! Or an end to the special counsel's funding!). Both parties ought to be united in opposition to that kind of tactic.

Instead, Washington seems to be caught in a spin cycle over whether the president's offer to freeze deportations for three years on Deferred Action for Childhood Arrival enrollees and non-citizens under Temporary Protected Status was good enough, or maybe the starting point for earnest negotiations. It may be the latter, but only after Trump agrees to stop the wasteful, record-setting (and not in a good way) shutdown.

– Jon Healey is a columnist for the Los Angeles Times.