Try it in the court of public opinion. Trump campaign can bring it to the attention of the public. If networks refuse to pursue it, make that a public charge of election interference by a foreign government. Get out in front of it and make it another black mark against Harris.
This close to the election that’s about all you can do and your suggestion is a good, importing foreigners to interfere in our election is similar to the Democrats importing foreigners to vote which they have done by the millions
YES!
Trump should make it abundantly and repeatedly clear to the Brit government that ANY participation by UK party members on US soil will be considered election interference and will absolutely harm our bilateral relations under a future Trump administration.