Story highlights The chairman of a subcommittee investigating Russia also wants information on Trump's business

Lindsey Graham's comments came the day after Sally Yates testified

(CNN) South Carolina Sen. Lindsey Graham said Tuesday he wants to explore whether there were any ties between President Donald Trump's businesses and Russia -- adding that the President's tax returns could be helpful to such an inquiry.

In an interview with CNN, Graham said he was intrigued by former Director of National Intelligence James Clapper's testimony Monday when he declined to comment over whether he had any concerns with Trump business ties and Russia, saying it could influence an ongoing investigation.

"I want to know more about Trump's business dealings," Graham told CNN Tuesday. "I asked Clapper. 'I said, 'Is there any business dealings with the Trump organization that gave you concern?' And he said, 'No,' with a caveat, 'I don't know what the FBI is looking at so I don't want to run afoul with them.'"

Graham cautioned that his judiciary subcommittee might have to "steer clear" of the matter if it conflicts with the FBI probe into Russia and the Trump campaign, and he said he also wants to learn about whether the identities of Americans were unmasked and unlawfully leaked to the press for political purposes. But he also signaled he was interested in learning more about the business ties.

Asked if Trump's tax returns could be helpful to such an investigation, Graham said: "It could be, down the road."

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