The historic removal of the House speaker Kevin McCarthy has thrown further doubt over the future of US support for Ukraine and resistance against Russia’s invasion. The latest tranche of $300m (£247m) in aid to Ukraine was approved overwhelmingly by the House last Thursday in a 331-117 vote, but all the 117 no votes were Republicans – more than half the party’s representatives. It was the far right of the party that ousted McCarthy and will be critical to the election of his replacement, as it is focused on cutting US funding for Kyiv. The choice of a new speaker will be all-important for Ukraine’s hopes for continued assistance, as they could stop funding bills even reaching the floor of the House for a vote. Joe Biden said at the weekend that US support for Ukraine could not be interrupted “under any circumstances”, and he can still count on bipartisan support for that position in the Senate, but sentiment among House Republicans is moving steadily against him. The contenders for McCarthy’s job hold a range of views on supporting Ukraine. The advocacy group Defending Democracy Together rates them on a scale of A to F, with A signifying the strongest support. Steve Scalise, the number two House Republican and the leading candidate so far, scored a B, one notch up on McCarthy’s B-. But other contenders such as Jim Jordan and Kevin Hern scored Fs, as did Matt Gaetz, who led the campaign to topple McCarthy and will be influential in the choice of successor. Jordan said on Wednesday he would not support continued aid to Ukraine if elected speaker. A poll published on Wednesday by the Chicago Council on Global Affairs showed that six in 10 Americans still support economic and military aid to Ukraine but that support is steadily waning, particularly among Republicans. In the immediate aftermath of the full-scale invasion last year, support for military aid to Ukraine was about 80%, from Democrats and Republicans alike. Democratic backing has declined only marginally, but enthusiasm among Republicans has plummeted to 50%. Ukraine supporters in the field of Republican presidential contenders are trailing badly, and the members of Congress report an increasing number of calls from constituents, concerned that taxpayers’ funding is being squandered in Ukraine, a theme being hammered home in rightwing media. Elon Musk, the owner of the X, formerly known as Twitter, has used the platform this week to ridicule the Ukrainian president, Volodymyr Zelenskiy, for his repeated requests for funding.