Senate Democrats are threatening to block legislation that would fund the Department of Homeland Security and several other agencies Thursday, potentially bringing the government a step closer to a partial shutdown if Republicans and the White House do not agree to new restrictions on President Donald Trump's surge of immigration enforcement.

Democrats are hoping for an upset in a special runoff election for a state Senate seat in Texas on Saturday. Democrat Taylor Rehmet, a local union leader, is facing off against Republican Leigh Wambsganss,

“Tonight is a wakeup call for Republicans in Tarrant County, Texas, and the nation. The Democrats were energized. Too many Republicans stayed home," she wrote.

The Senate is expected to vote on a war powers resolution that would prevent President Trump from taking any further military action in Venezuela on Wednesday. Last week, five Senate Republicans voted to advance the measure — a sharp rebuke of the president.

The deal could be approved by the Senate as early as Thursday night, but would still need House approval before midnight Friday to avert another government shutdown.