CNN's Manu Raju reported last week that Republicans had warned Pompeo that he would face "a brutal onslaught" if he were to run and went as far as hiring a retired FBI agent to look into Pompeo's background.
Multiple senators urged Pompeo to abandon his plans and House Speaker Paul Ryan (R-WI) called Pompeo personally, according to the report. Pompeo ultimately decided not to run.
In the months before President-elect Donald Trump's election victory, Republican lawmakers had scrambled to defend vulnerable GOP senators whose campaigns were overshadowed by Trump's unconventional bid.
The National Republican Senatorial Committee focused on defending its majority in the chamber at the beginning of the 2016 election cycle, and that strategy included discouraging Pompeo's potential run against Sen. Jerry Moran (R-KS).