Congressional Republicans are demanding an 11th-hour change to Nebraska’s presidential voting system in a move that could transform the electoral calculus and tip the race to Donald Trump in the event of a photo finish.

With polls showing Trump neck-and-neck with Kamala Harris both nationally and in battleground states, senior GOP congressional figures are pressing the Nebraska legislature to replace a system that splits the allocation of its electoral college votes with the straightforward winner-takes-all distribution that operates in most US states.

The change would increase the number of electors allotted to Trump for winning the solidly Republican state from four to five – and raises the possibility that the former president could end up tied with Harris at 269 electoral votes each.

Such a scenario would pitch the ultimate decision on the election into the House of Representatives, which has the constitutional authority to certify the results – meaning the outcome of November’s House election, in which Republicans are defending a wafer-thin majority, could be even more pivotal than usual.

In a sign of the raised stakes, the South Carolina senator Lindsay Graham – a close Trump ally – visited Nebraska this week and urged legislators to find the extra votes needed to revert its electoral college distribution procedure back to the winner-takes-all system it used before 1992.

Pressure was also ratcheted up by the state’s five US congressional members, who wrote to Nebraska’s governor, Jim Pillen, and the speaker of its single-chamber legislature, John Arch, who are both Republicans.

“As members of Nebraska’s federal delegation in Congress, we are united in our support for apportioning all five of the Nebraska’s electoral votes in presidential elections according to the winner of the whole state,” read the Nebraska delegation’s letter, posted on X by GOP House member Mike Flood, one of its signatories. “It is past time that Nebraska join 48 other states in embracing winner-take-all in presidential elections.”

Potential for a Tie

A two-thirds majority of the Republican-led chamber is needed to change the system. Only 31 or 32 of the 50-seat body are thought to be in favour, meaning the spotlight is being focused on the state senator Mike McDonnell, a former Democrat who turned Republican this year but swore he would never support winner-takes-all.

Local media reports have depicted McDonnell as wavering amid speculation that Trump may soon contact him personally.

The issue is potentially vital because some pollsters have predicted that Harris is on course to win exactly the 270 electoral votes needed to capture the White House by winning the three northern swing states of Pennsylvania, Michigan and Wisconsin, where recent polling has shown her with small but consistent leads.

However, she would fall short by just one if a winner-takes-all distribution was adopted in Nebraska, whose second congressional district – encompassing the state’s largest city, Omaha, and its suburbs – together with its single electoral vote is expected to fall to Harris, as it did to Joe Biden in 2020.

A Last-Minute Push

To avoid a tie, Harris would need to win the three northern battlegrounds along with at least one of four southern Sun belt states – North Carolina, Georgia, Nevada and Arizona – where she and Trump are deadlocked, but where polls often show the former president with a tiny edge.

Unlike most other states, Nebraska does not allocate its electoral votes to the presidential candidate who wins the popular vote, but instead gives that candidate two electoral votes while awarding the rest on the basis of which party wins its three congressional districts.

Maine is the only other state to operate a comparable system. This year, its Democratic house majority leader vowed that it would cancel out any move in Nebraska to revert to a winner-takes-all approach by introducing a similar change in Maine.

However, by leaving the push until less than seven weeks before the 5 November election, Republicans may have blocked off that option.

Maine’s legislative rules deem that a bill can only become law 90 days after its passage, unless it is passed with two-thirds majorities in both chambers, meaning there will be insufficient time to implement a new system by polling day. Although Democrats have majorities in the state’s house and senate, they do not have supermajorities.

Potential Backlash

The Nebraska Republicans may be gambling that they can secure McDonnell’s vote. This could be crucial in a highly contested election. However, there is a possibility that the change could backfire. It has been argued that the change could backfire and cause more harm than good to the GOP.

The Open Democracy PAC, a progressive political action committee, has released a memo that suggests the change could lead to a backlash from voters in the Omaha area. The PAC argues that Trump may be forced to abandon Omaha if the winner-takes-all system is enacted, which could ultimately benefit Democrats in the region.

The memo also cites polling that suggests voters in Omaha would be less likely to vote for candidates they otherwise agree with if the candidates supported the change.

The move by Republicans could further exacerbate an already tense political climate. The situation in Nebraska is another example of how the 2024 presidential election is becoming increasingly unpredictable.

The stakes are high. If Republicans are able to pass the legislation, it could have a significant impact on the outcome of the election. However, it could also lead to a backlash from voters in Omaha, who may be less likely to vote for Republicans in the future.