WASHINGTON — President Donald Trump on Wednesday grudgingly signed a bipartisan bill imposing fresh sanctions on Russia, citing “clearly unconstitutional provisions” and criticizing as “significantly flawed” the curbing of his executive authority.

He said he approved the legislation for the “sake of national unity,” but attacked his GOP colleagues by positing himself as the superior negotiator and deriding their failure to fulfill their long-standing pledge to repeal and replace Obamacare.

“I built a truly great company worth many billions of dollars. That is a big part of the reason I was elected,” he said in a statement. “As President, I can make far better deals with foreign countries than Congress.”

The “Countering America’s Adversaries Through Sanctions Act” enjoyed wide support from lawmakers of both parties as a collective condemnation of Moscow for its cyberattacks during the 2016 U.S. election and other transgressions.

It notably requires the president to submit for congressional review proposals to terminate or waive penalties against Russia.

It also expands sanctions on Iran and North Korea for their ballistic missile programs.

Congress passed the bill with veto-proof margins. The House approved it 419-3 and the Senate, 98-2.

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The economic sanctions were served up by Capitol Hill amid ongoing FBI and congressional investigations into Russian meddling in last year’s election and as the Trump administration seeks to reset relations with the Kremlin.

Moscow has signaled its displeasure.

Russia Prime Minister Dmitry Medvedev wrote on Facebook: “The Trump administration demonstrated complete impotence, transferring executive powers to Congress in the most humiliating manner.”

On Sunday, President Vladimir Putin had retaliated with the expulsion of hundreds of American diplomats.

Trump has acknowledged the U.S. intelligence community conclusion that Russia was a threat to the U.S. election process, but hasn’t been as definitive as other Republican Party leaders.

“I think it was Russia, and I think it could have been other people and other countries,” he said last month in Poland.

Trump predicted Wednesday that cooperation with Putin on “major global issues” would render the penalties unnecessary.

White House press secretary Sarah Huckabee Sanders said Trump did not speak with Putin before he signed the bill.

She said he moved the measure along to punish the “rogue regimes in Iran and North Korea” and send a “clear signal that we won’t tolerate interference in our democratic process by Russia.” She said Trump’s issues were more about the process than the principles of the bill.

Democrats underscored Trump’s reluctance to back the bill.

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Senate Minority Leader Chuck Schumer (D-N.Y.) said Trump’s statement “demonstrates that Congress is going to need to keep a sharp eye on this administration’s implementation of this critical law and any actions it takes with respect to Ukraine.”

House Minority Leader Nancy Pelosi (D-Calif.) said it raises “serious questions about whether his administration intends to follow the law, or whether he will continue to enable and reward Vladimir Putin’s aggression.”

Trump stressed that he successfully negotiated some modifications in the sanctions legislation, but took shots at lawmakers for handcuffing his ability to broker deals with foreign powers.

“Congress could not even negotiate a health care bill after seven years of talking,” the president said. “By limiting the executive’s flexibility, this bill makes it harder for the United States to strike good deals for the American people, and will drive China, Russia and North Korea much closer together.”

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