President Donald Trump lashed out at two Republican senators recently over matters relating to Russia, according to a Politico report on Wednesday, showing the degree to which the unfolding Russia scandal is keeping the president occupied.

First, in a late-July phone call with Tennessee Sen. Bob Corker, Trump complained about a bipartisan bill that sanctioned Russia for interfering with the 2016 US election while making it tougher for Trump to lift the sanctions. The bill was overwhelmingly supported in Congress by both parties and was signed into law earlier this month.

“He was clearly frustrated,” a source familiar with the call told Politico.

Then, on August 7, Trump called Sen. Thom Tillis of North Carolina to express his unhappiness with a bill that would limit Trump’s ability to fire Robert Mueller, the special counsel investigating the Trump campaign’s potential ties to Russia’s election interference. Trump said he didn’t want the bill to pass, according to another Politico source familiar with the call.

The two calls underscore Trump’s increasing frustration with Congressional Republicans over their continued efforts to keep the Russia probe alive. Trump also lashed out at Senate Majority Leader Mitch McConnell in a profane phone call earlier this month relating to the sanctions bill.

"It seems he is just always focused on Russia," a senior Republican aide told Politico.

White House deputy press secretary Lindsay Walters acknowledged the two private calls, but did not offer specifics.

"We do not comment on private conversations the president has with members of Congress," Walters said in a statement. "We are committed to working together on tax relief, border security, strengthening the military, and other important issues."

But with each new quarrel with a fellow Republican, Trump strains the relationship between him and the Congress members who he needs to pass his agenda.

Trump has openly courted challengers to oust Republican Sen. Jeff Flake, who he called "weak on borders" for opposing Trump's plan to build a wall along the US-Mexican border. And he has threatened political retaliation against Republican senators who wavered on the GOP replacement health care bill, including Dean Heller of Nevada, who ultimately voted for the bill, and Lisa Murkowski of Alaska, who didn't.

The bill ultimately failed by one vote, delivering another defeat to the White House.