All 47 Senate Democrats were silent when asked by The Daily Signal whether they support a pending bill to compel proof of citizenship for voters in federal elections.

But the Safeguard American Voter Eligibility Act, or SAVE Act, is gaining momentum among Senate Republicans.

The House passed the SAVE Act on Wednesday by a 221-198 vote. The legislation would amend the 1993 National Voter Registration Act, known as the “motor voter law,” to require that states obtain documentary proof of U.S. citizenship from someone before he or she may register to vote in federal elections.

The companion bill in the Senate, introduced by Sen. Mike Lee, R-Utah, has 20 co-sponsors—a significant spike from its original seven.

“Only Americans should vote in American elections,” Lee told The Daily Signal. “I challenge my Democrat colleagues to explain to the American people why they think noncitizens should be able to fraudulently cast ballots.”

Although five House Democrats voted for the bill sponsored by Rep. Chip Roy, R-Texas, the other 198 House Democrats voted against it.

Not a single Senate Democrat responded to The Daily Signal’s requests for comment on how they would vote on the SAVE Act.

“The SAVE Act is the most common sense legislation possible,” Lee said, “and the vast majority of Americans agree that our elections should be protected from illegal foreign interference.”

President Joe Biden has vowed to veto the measure if it passes the Senate and goes to his desk.

“Almost every single Democrat voted against requiring proof of citizenship to vote,” Sen. Ted Cruz, R-Texas, told The Daily Signal, referring to the House vote on Wednesday. “The Democrats want illegal aliens to vote because they think they’re going to vote for Democrats—even though it’s illegal for illegal aliens to vote. Just about every Democrat yesterday voted against requiring proof of citizenship, and so we’re going to fight for this.”

Sen. Joni Ernst, R-Iowa, said every state should follow Iowa’s example by requiring proof of citizenship to vote.

“As Democrats show they are adamantly against ensuring only American citizens vote in American elections,” Ernst said, “we must do more to secure election integrity.”

Sen. Bill Cassidy, R-La., supports Lee’s bill, according to his office.

“Sen. Cassidy absolutely believes illegal immigrants should not be voting in federal elections,” a spokesperson said.

As one of the bill’s co-sponsors, Sen. Rick Scott, R-Fla., said he “absolutely” supports the SAVE Act.

“Illegals should never be allowed to vote in our elections,” Scott told The Daily Signal, “but unfortunately Biden and his radical Democrats are trying to give illegals more rights, support, and resources than are given to law-abiding American citizens.”

Sen. Marsha Blackburn, R-Tenn., said it is “plain and simple” that illegal immigrants shouldn’t vote in U.S. elections.

“The SAVE Act would close existing loopholes in the National Voter Registration Act to require every potential voter in every state to prove they are an American citizen before casting their vote in a federal election,” Blackburn told The Daily Signal.

Fred Lucas contributed to this report.