Republican leaders in the Pennsylvania Senate introduced legislation Monday that would effectively prohibit the use of mail-ballot drop boxes that President Donald Trump has criticized, make it more likely that a winner in the presidential race is known soon after polls close, and reduce the number of ballots rejected for arriving late.

But the proposal also would give voters less time to request mail ballots, prompting Gov. Tom Wolf, a Democrat, to quickly come out against it. That left it unclear Monday whether a fierce political and legal battle over mail voting in a key swing state would be resolved in the state legislature or in the courts.

The changes, along with others in the proposal, would have a significant impact on how votes are cast and counted in an election little more than two months away. The bill was introduced by Senate President Pro Tempore Joe Scarnati (R., Jefferson) and Majority Leader Jake Corman (R., Centre), suggesting it has the necessary support to pass the Senate.

“This bill will go a long way toward providing additional confidence in our election process and the results by taking steps needed to increase election access, accountability, and security,” Corman said in a statement.

Much of the legislation is focused on mail ballots, which have been the subject of intense scrutiny across the country as Trump has falsely assailed them as prone to widespread fraud, and as mail delivery delays have raised alarm about votes being delivered on time. The use of mail ballots is surging in Pennsylvania and across the country amid coronavirus fears of in-person voting.

The Senate Republicans’ proposal would move the deadline to apply for a mail ballot earlier, from seven days before Election Day to 15. That would widen the window between requesting and returning a ballot, potentially reducing the number of ballots rejected. But it would also give voters less time to request them.

That’s why Wolf opposes the proposal, said Lyndsay Kensinger, his spokesperson: “The governor is opposed to any proposal that would limit Pennsylvanians’ ability to vote.

“This proposal appears to do so by limiting the ability for individuals to cast mail ballots by reducing the number of days Pennsylvanians can request one,” she said. “The governor will only support an election reform proposal that makes it easier and safer for Pennsylvanians to cast their ballots.”

The legislation would allow voters to physically bring their completed mail ballots to their assigned polling places on Election Day, to county courthouses, or to “the permanent offices of the county board of elections.” That language, however, would likely block counties from setting up satellite offices for early voting and drop boxes, because mail ballots would be returnable to “no other location.”

“They want us to give up the drop boxes. Obviously that is in tune with what Trump’s campaign wants,” said State Rep. Kevin Boyle, the ranking Democrat on the House State Government Committee, which takes up election legislation. “That is particularly troublesome due to the issues” with the U.S. Postal Service.

The bill came as a new election law expanding mail voting, the pandemic, and the mail delays have, taken together, created a fever pitch of anxiety around the process of running the election. There are ongoing court battles over the election and, now, the possibility of protracted negotiations in the legislature.

The resulting uncertainty around fundamental rules of how votes can be cast and counted risks confusing voters. It also makes it difficult for elections officials to prepare. Just last week, the Pennsylvania Department of State issued new guidance to counties on how to set up drop boxes. Those would not be legal under the Senate Republicans’ proposal, and the Trump campaign is suing Pennsylvania in federal court to block their use.

A federal judge in western Pennsylvania put that lawsuit on hold over the weekend while other litigation proceeds in state courts. On Monday, Trump took to Twitter to falsely assail drop boxes as a “voter security disaster” that “make it possible for a person to vote multiple times” and are “not Covid sanitized.” Twitter later attached a warning notice to that post saying it violated its rules against vote suppression.

Pennsylvania and other states are also suing the Postal Service over the mail delays. And the Pennsylvania Department of State has asked the state Supreme Court to order that mail ballots be counted as late as three days after the election.

The Biden campaign declined to comment on the proposal late Monday. The Trump campaign didn’t immediately respond to a request for comment.

Legislative leaders and the governor’s office have been discussing election legislation throughout the summer, and Scarnati said in a statement Monday that “we look forward to working with the House of Representatives and Wolf administration to ensure these crucial reforms are in place for the upcoming election.”

But the proposed legislation clearly took some leading Democrats in the state House and Senate by surprise.

“This was not the product of negotiations between Democrats and Republicans,” said Boyle, who represents Northeast Philadelphia. “This was news to me.”

State Sen. Sharif Street, a Philadelphia Democrat and vice chairman of the state party, said that if the GOP proposal is “the opening salvo in a meaningful conversation, we’re willing to engage.” But he expressed concern about how the bill would impact drop boxes.

A spokesperson for Republicans in the State House didn’t comment late Monday. A House GOP source, granted anonymity to discuss internal negotiations, said Democratic lawmakers were not involved in the talks between Republicans and the Wolf administration over the proposal. Wolf’s spokesperson said the administration was aware of the Republican proposal prior to its release but had yet to provide final feedback.

Counties would be required to “pre-canvass” mail ballots before Election Day under the legislation, opening and counting those ballots as early as 8 a.m. Saturday but not recording or publishing the results, making it easier for a winner to be known earlier after polls close. Currently, mail ballots cannot be opened until Election Day, meaning it will likely take days to call some races.

Other changes include allowing voters to serve as poll watchers anywhere in the state, not only in their home county as current law requires, just as Trump has promised to have poll watchers across the country; allowing voters to serve as poll workers at any polling place in their county, not only in their home precinct; and requiring counties to email, call, or text any voters whose mail ballot signatures do not match what is on file so they can have an opportunity to fix their signatures before their ballots are rejected.

-Staff writer Julia Terruso contributed to this article.