President Donald Trump's first conversation with Russian President Vladimir Putin since taking office is sparking concern among European allies and his own Republican Party about the future of U.S. sanctions on Moscow.
Ahead of the call planned for Saturday, Trump was noncommittal about whether he was considering lifting the economic penalties.
He told reporters: "We'll see what happens. As far as the sanctions, very early to be talking about that."
Trump made those remarks Friday alongside British Prime Minister Theresa May, whose country — as part of the European Union — also levied sanctions on Russia following its provocations in Ukraine.
Voicing the view of many in Europe, May said, "We believe the sanctions should continue."
Vice President Mike Pence was expected to be on the Putin call with Trump.
He wasn't expected to join other diplomatic calls the president planned for Saturday.
Two top Senate Republicans — John McCain, the chairman of the Armed Services Committee, and Rob Portman, a member of the Foreign Relations Committee — also warned the White House about easing any punishments on Moscow and vowed to turn the sanctions into law.
"I hope President Trump will put an end to this speculation and reject such a reckless course," McCain said in a statement. "If he does not, I will work with my colleagues to codify sanctions against Russia into law."
Portman said lifting the sanctions "for any reason other than a change in the behavior that led to those sanctions in the first place would send a dangerous message to a world already questioning the value of American leadership and the credibility of our commitments after eight years of Obama administration policies."
U.S. intelligence officials have concluded that Moscow meddled in the 2016 election to help Trump become president.
Obama in late December ordered sanctions on Russian spy agencies, closed two Russian compounds and expelled 35 diplomats the U.S. said were really spies.
The new penalties add to existing U.S. sanctions over Russia's actions in Ukraine, which have damaged Russia's economy but only limited impact on Putin's behavior.
In 2014, Russia annexed Crimea in Ukraine, drawing widespread condemnation in Europe and the United States and a raft of penalties.
For his part, McCain has emerged as a frequent critic of Trump among Capitol Hill Republicans. He takes a dim view of trying to reset relations with Moscow and says Trump should remember that Putin is "a murderer and a thug who seeks to undermine American national security interests at every turn."
"For our commander in chief to think otherwise would be naive and dangerous," McCain said.
McCain and Portman are part of a bipartisan group of senators who have introduced sweeping legislation designed to go beyond the punishments against Russia already levied by Obama and to demonstrate to Trump that forcefully responding to Moscow's meddling isn't a partisan issue.
The bill would impose mandatory visa bans and freeze the financial assets of anyone who carries out cyberattacks against public or private computer systems and democratic institutions.
The legislation also mandates sanctions in Russia's all-important energy sector and on investments in the development of civil nuclear projects to rebuke Moscow for its provocations in eastern Ukraine and military support for Syrian President Bashar Assad.