What to do about Russian money poisoning US elections?

Santos is only the most recent example

Russian money has been finding its way into American elections. It’s a growing threat to U.S. national security and to the integrity of our election system. In ironic contrast to the GOP’s baseless claims of fraudulent Democratic voting, this flow of Russian money especially implicates the Republican Party.

For example:

Serial liar Rep. George Santos (R-NY) appears to have had money funneled into his 2022 campaign from the cousin of a sanctioned Russian oligarch.