WASHINGTON — With a partial government shutdown stretching past Day 5, the impasse over funding a wall at the southwestern border has highlighted the debate over effective border security, with a breakthrough possibly hinging on a semantic argument: What is a wall?

Lawmakers will return to Capitol Hill on Thursday to resume negotiations over either a stopgap spending bill to reopen nine federal departments and several government agencies or broader measures to fund the government through September. But the White House and Democrats remain at odds over the $5 billion that President Trump is demanding for a wall, his signature campaign promise.

Representative Steve Scalise of Louisiana, the majority whip, told House members on Wednesday that no votes were expected on Thursday. That signaled that the shutdown would almost certainly stretch through the weekend — and probably into the new year. More than likely, it will fall to House Democrats to pass legislation reopening the government when they take control on Jan. 3.

[How the shutdown affects federal departments.]

The president told reporters on Wednesday that he would do “whatever it takes” to ensure funding was provided for the wall he once bragged Mexico would pay for.