The federal budget expires at the end of September, and a disruption in funding would have a major impact on troops and veterans.

WASHINGTON — President Donald Trump on Tuesday vowed to “close down our government” if Congress doesn’t provide him funding for a controversial wall along the southern American border, once again raising the prospect of a disruptive federal shutdown in the weeks ahead.

At a campaign-style rally in Phoenix, Trump blasted “obstructionist Democrats” opposed to constructing the massive border wall, one of the president’s signature pre-election promises. He called it a national security issue and hinted he would not sign any budget deals that omitted funding for the project.

“Believe me, if we have to close down our government, we’re building that wall,” he told a crowd of supporters. “Let me be very clear to Democrats in Congress who oppose a border wall and stand in the way of border security: You are putting all of America’s safety at risk. You’re doing that.”

Democrats have staunchly opposed the idea of providing $1.6 billion in preliminary wall funding in the fiscal 2018 budget. Party leaders have been negotiating with Republican officials for months on a possible compromise path before Sept. 30, when the current budget resolution expires.

But if a long-term plan or short-term extension isn’t agreed upon in the next five weeks, or if Trump opposes any deal worked out by Congress, the disagreement would trigger a partial government shutdown, which would impact services for troops, their families and veterans.

The last extended government shutdown occurred in October 2013, resulting in unpaid furloughs for civilian workers employed by the departments of Defense and Veterans Affairs.

Service members’ duties continued uninterrupted, but some military pay and benefits were delayed during the 18-day shutdown. In addition, services like daycare and commissary operations on military installations were disrupted or cut back.

A partial shutdown would not affect most VA operations, since Congress included advanced appropriations for fiscal 2018 in last year’s budget vote to avoid significant shutdowns of VA health and benefits services.

However, non-essential services — information hotlines and veterans job service programs funded through other departments — would be stalled during a shutdown.

Lawmakers on both sides have repeatedly said they are against the idea of another shutdown, and are confident they can reach some compromise before then.

Whether Trump’s comments Tuesday night will erase that optimism won’t be evident until early next month, when lawmakers return from summer recess to deal with the looming budget issue.

At the event, Trump accused Democrats of supporting ruinous fiscal policies, asserting that “under their plan for America, your taxes will double or triple, your service will diminish and your borders will be left wide open for everybody to come in and enjoy our country.”

But he also criticized Republicans in Congress for not taking a harsher tone with their political opponents, in particular attacking senators inability to repeal the Affordable Care Act earlier this summer.