US House Speaker Mike Johnson has called for Ukraine to dismiss its ambassador to Washington amid escalating tensions between the Republican Party and Ukrainian President Volodymyr Zelensky.

The conflict intensified after Zelensky visited an arms factory in Scranton, Pennsylvania — President Joe Biden’s hometown and a key swing state — alongside prominent Democrats. Johnson criticized the visit in a public letter, accusing Zelensky of engaging in “election interference” by aligning with Democrats and claimed it was intended to boost the party’s chances in upcoming elections.

The dispute threatens to overshadow Zelensky’s upcoming meeting with President Biden, where the Ukrainian leader is expected to present a “plan for victory” in Ukraine’s war against Russia. Zelensky’s visit has been focused on securing additional support from the US and other allies as his country continues to resist Russian aggression.

Ahead of his White House meeting, Zelensky outlined three key elements of his victory plan: increased military aid, diplomatic efforts to push Russia towards a peace agreement, and holding Moscow accountable for the 2022 invasion.

Zelensky had initially planned to discuss these proposals with both US presidential candidates, Kamala Harris and Donald Trump. However, Trump’s campaign indicated that the Republican nominee would not meet with Zelensky during his US tour. Trump and Zelensky have a strained history, with Trump having been impeached in 2019 over allegations that he pressured Ukraine’s leader to investigate a political rival.

Trump has recently criticized Zelensky, accusing him of refusing to negotiate with Russia and mocking him as the “greatest salesman on Earth” during a campaign event. At a separate rally, Trump praised Russia’s military, highlighting their historical victories over Napoleon and Hitler.

The tension has been exacerbated by Zelensky’s Scranton visit, where he appeared alongside Pennsylvania Governor Josh Shapiro and other Democrats. Johnson accused Zelensky of participating in a “partisan campaign event” to support Vice President Kamala Harris’ campaign.

The Republican-led House Oversight Committee has announced an investigation into whether Zelensky’s visit was an attempt to influence the upcoming election in favor of Harris.

Congressional Republicans previously blocked the Biden administration’s $61 billion military aid package for Ukraine, only relenting in April after a months-long delay that temporarily halted arms supplies. Despite this, the US remains Ukraine’s largest foreign donor, having provided $56 billion in military assistance to date.