Washington CNN  — 

GOP Sen. Jeff Flake gave some of his harshest criticism of President Donald Trump to date in a commencement speech Wednesday to Harvard Law students, where he shared his concerns for the integrity of politics in the United States.

The Arizona senator, who has announced he will not be seeking re-election in 2018, has said he will use his remaining time in the Senate to speak out against the President when he believes it is warranted.

“Not to be unpleasant, but I do bring news from our nation’s capital. First, the good news: Your national leadership is … not good,” he said at the commencement Wednesday. “At all. Our presidency has been debased. By a figure who has a seemingly bottomless appetite for destruction and division. And only a passing familiarity with how the Constitution works.”

He later continued: “Now, you might reasonably ask, where is the good news in that? Well, simply put: We may have hit bottom. Oh, and that’s also the bad news. In a rare convergence, the good news and bad news are the same: Our leadership is not good, but it probably can’t get much worse.”

In an interview with CNN’s “The Situation Room with Wolf Blitzer, Flake said his speech was about standing up and reclaiming “our constitutional prerogative.”

“Whether it’s passing immigration reform or authorization for use of force, we shouldn’t continually say ‘We’ll pass what the president wants,’ we should pass what we think we should do and ask the president to sign it. He can either sign it or veto it. But we’ve given far too much, and I think its time for the Congress to stand up.”

During his commencement address, Flake not only slammed the White House, but also blamed Congress, saying it’s “failing its constitutional obligations to counteract the power of the president, and in so doing is dishonoring itself, at a critical moment in the life of our nation.”

“It will be the work of your generation to make sure that this degradation of democracy does not continue – to see to it that our current flirtation with lawlessness and authoritarianism does not become a heritable trait to be passed down from this presidency,” he said.

He ended by telling the students they have the power to change the nature of the nation’s politics.

“We need each other, and it is a scoundrel who would prosper politically by turning us against each other,” he said. “That is the job before us – to get through this, and beyond it. And you’re just the ones to take us there.”

CNN’s Sophie Tatum contributed to this report.