Senator Thom Tillis of North Carolina sharply criticized the SAVE America Act during a Senate floor speech on Thursday, vowing to obstruct the legislation.
The House of Representatives passed the SAVE America Act on Wednesday as part of a national security package.
On Thursday, the House Budget Committee advanced the measure through the budget reconciliation process and approved a framework for a third reconciliation bill.
Reconciliation would let the Senate pass the bill with a simple majority instead of the 60 votes normally needed to break a filibuster, though Senate rules will decide which provisions qualify.
Tillis warned he would use every available procedural tool to slow the legislative process if the House sends a reconciliation bill he views as an attempt to confuse the election.
He argued the proposal cannot be implemented before the election, stating it should have been addressed two years earlier.
The senator also dismissed the SAVE Act and related House proposals as fundamentally flawed and mocked the repeated iterations of the legislation.
President Trump has urged the Senate to pass the SAVE America Act, framing voter identification as a requirement no American should oppose.
A previous statement from the White House said registering to vote in the United States should require citizenship and supported the legislation on that basis.
The White House had cited polling indicating more than 70% of Americans back the SAVE America Act.
