House Speaker Paul Ryan says Attorney General Jeff Sessions should only recuse himself from a Justice Department investigation into Russian interference in the presidential election if Sessions is a subject of the probe.

Ryan says Congress has been “presented with no evidence that anyone on the Trump campaign or an American was involved in colluding with the Russians.”

Democrats have demanded Sessions’ resignation after the revelation that he had twice talked with Moscow’s U.S. envoy during the campaign. Sessions’ conversations seem to contradict Sessions’ sworn statements to Congress during his confirmation hearings.

Ryan says Republicans will “leave no stone unturned” in their own investigations of ties between Russia and Donald Trump’s presidential campaign, which the House and Senate Intelligence Committees are conducting.

WATCH: House minority leader Pelosi comments on Sessions’ role in Russia probe