Sen. Bob CorkerRobert (Bob) Phillips CorkerVoters will punish Congress for ignoring duty on war and peace GOP senator reviving effort to rein in Trump on tariffs Trump draws bipartisan fire over Brennan MORE (R-Tenn.) called on President Obama to urge European allies to help Ukraine by increasing sanctions against Russia.

“I am pleased the president signed our bill into law, and I hope he will do the hard work to convince the Europeans to adopt similar measures and stand with Ukraine against the ongoing threat of Russian aggression,” Corker said on Thursday.

His comments came after Obama signed the Ukraine Freedom Support Act into law. Corker helped author the bill that increased economic pressures on Russia’s energy and defense sectors.

Corker said the legislation is necessary if the United States wants to curb Russian aggression against Ukraine. Russian President Vladimir Putin has already annexed Crimea and has supported separatist movements within eastern Ukraine.

“I would urge the president to use the tools provided to help restore Ukraine’s leverage in negotiations and de-escalate this crisis instigated by Russia’s hostile actions,” Corker said.

The administration's sanctions against Russian leaders have begun to make themselves felt by the economy, as a crumbling ruble indicates.