South Carolina Sen. Lindsey GrahamLindsey Olin GrahamTrump stuns the world at Putin summit Overnight Defense: Washington reeling from Trump, Putin press conference Ryan: 'The president must appreciate that Russia is not our ally' MORE (R) said Wednesday he would lead a charge to investigate Russia's interference in the U.S. election and hacks on the Democratic Party.

"I think [Donald] Trump should take a real tough tone with Russia, because if he doesn't, you're going to allow Russia to begin to break apart alliances," Graham told CNN's Manu Raju.

The Republican senator also said he hoped to use his leadership role on two subcommittees to launch a deeper investigation of Russia's hacks, CNN reported. Graham chairs the State, Foreign Operations and Related Programs subcommittee and the Crime and Terrorism subcommittee.

Raju said Graham told him that he and Sen. John McCainJohn Sidney McCainGOP lambasts Trump over performance in Helsinki Trump stuns the world at Putin summit NY Daily News cover following Helsinki summit shows Trump shooting Uncle Sam MORE (R-Ariz.), chair of the Armed Services Committee, will travel to Eastern Europe to investigate Russian meddling in other countries' elections.

During the campaign, Graham was a strong GOP critic of Trump, including on his friendlier stance toward Russia, and chose to vote instead for independent candidate Evan McMullin.