A bipartisan group of senators reached a deal on Wednesday to reform a federal law and prevent a future presidential candidate from overturning the will of the people and the result of a valid presidential election.

The lawmakers have agreed to two bills that would reform the Electoral Count Act of 1887, which governs how electoral votes are counted following a presidential election. Citing ambiguities in the law, Donald Trump and his attorneys pushed his vice-president, Mike Pence, to disrupt the counting of electoral votes that showed he lost the 2020 election, escalating calls for the 135-year-old law to be reformed. Even before the election, experts warned the law was ambiguous and could be exploited.

“Through numerous meetings and debates among our colleagues as well as conversations with a wide variety of election experts and legal scholars, we have developed legislation that establishes clear guidelines for our system of certifying and counting electoral votes for president and vice-president. We urge our colleagues in both parties to support these simple, commonsense reforms,” the group of 16 senators said in a joint statement. Senators Joe Manchin and Kyrsten Sinema, the two Democrats who stymied more sweeping voting rights reform earlier this year, are among the group that developed the proposal. Republicans in the group include Maine senator Susan Collins, South Carolina senator Lindsey Graham and North Carolina senator Thom Tillis.

The first bill is called the Electoral Count Reform and Presidential Transition Improvement Act, and would fix ambiguities in the existing law while clarifying when an incoming administration can access federal resources.

Under current law, Congress has to consider an objection to the counting of electoral votes if just one member of each house objects. One of the proposed bills would raise that threshold, requiring the support least 20% of members in each house to consider an objection. The bill also creates a judicial process with expedited review, first by a three-judge panel then by the US supreme court, over certain matters related to disputed electors.

In 2020, Trump and allies encouraged submitting alternative slates of electors in key swing states Trump lost. The new law clarifies that only the slate of electors officially approved by the state’s governor can be submitted to Congress. It also clarifies the term “failed election” used in another 19th century law, saying that a state can move its presidential election only if there were “extraordinary and catastrophic events”. There were concerns in 2020 that ambiguities in that language could be used by state legislatures to throw out the popular vote.

After Trump insisted Pence had the authority to unilaterally throw out electoral votes, the bill makes certain that the vice-president has no such authority. It makes clear that the vice-president’s presence at the counting of electoral votes is solely in a ministerial role.

The bill also clarifies that both presidential candidates should get access to presidential transition funds while an election result is disputed. Trump delayed giving Joe Biden access to resources to transition in the White House after the 2020 election.

The Enhanced Election Security and Protection Act is the second proposal, and would up criminal penalties against people convicted of intimidating or threatening candidates, voters and poll workers, amid a significant uptick in threats after 2020. It increases the maximum penalty for those who make threats from one to two years in prison.

The bill would require election records to be preserved, help the US Postal Service deal with mail-in ballots and reauthorize for five years a commission that works with states to improve their voting practices.