Sen. John McCain took a stand for honor and country last week in sharp contrast to the self-obsessed showman in the White House.

The Arizona Republican summoned the strength to return to Congress after a brain cancer diagnosis to urge fellow senators to halt the ugly partisanship that is destroying our institutions. Meantime, President Trump was busy tweeting threats to fire his top officials and undercutting any chance for coherent domestic or foreign policies.

McCain's statesmanship stood in stark contrast to the circus in the White House, where a willfully ignorant president is emboldening our adversaries and could provoke a war.

When McCain cast the vote that finally scuttled GOP repeal of the Affordable Care Act his intent went beyond the health-care issue. His real objection was to the secretive Republican process that failed to produce any credible replacement for Obamacare and would have made health care worse, not better.

The last GOP "skinny repeal" bill, which the Arizonan nixed, was so bad that most Republican senators disliked it, but were ready to pass it just so Trump could chalk up a "win."

In a moving floor speech last week McCain warned of a U.S. Senate that was "more partisan, more tribal, more of the time than any other time I remember." He pleaded for senators to recognize that the genius of our democratic system - which made it different from "cruel" autocracies - was its recognition that compromise is needed in order to reach solutions.

He urged a return to "the old way of legislating in the Senate" with hearings and bipartisan input. "It is our responsibility to preserve that," he urged, "even when it requires us to do something less satisfying than 'winning.'"

The jab at the president could not have been more clear.

And McCain offered another pertinent caution. "Stop listening to the bombastic loudmouths on radio and television and the Internet," he advised. "To hell with them. They don't want anything done for the public good."

Meantime, the Tweeter-in-chief was busy illustrating just what McCain was warning about.

Instead of leading on health care, he spent the week tweeting a stream of grotesque insults at Attorney General Jeff Sessions, one of Trump's most loyal backers. Lacking the guts to fire Sessions, he was trying to goad the AG to quit.

Then - in case the world wasn't already convinced the White House had gone mad - Trump brought in plutocrat pal Anthony "the Mooch" Scaramucci as his chief "communications" director. He promptly let loose a foul, expletive-laced public rant against White House chief of staff Reince Priebus and Trump's chief strategist, Steve Bannon - a clear warning their jobs were endangered.

The Mooch was clearly fronting for Donald "You're fired" Trump, with whom he had just had dinner. The president replaced Priebus Friday.

This White House reality show endangers the republic as McCain knows only too well.

Beyond his domestic failures, the president's antics destroy any coherent foreign policy process. Trump publicly countermands Secretary of State Rex Tillerson on important issues - such as Iran and the Arab Gulf - to the extent that Tillerson has denied he is quitting. Rumors swirl about the future of National Security Adviser H.R. McMaster, who is openly challenged in the White House by Bannon.

Meantime, Trump openly insults his intelligence agencies and continues to refute their conclusion that Russia hacked the 2016 election. And the president plays fast and loose with the Pentagon, ignoring normal policy processes. Just last week, he tried to ban transgender service members from serving - via a tweet - without first informing the Pentagon or military brass.

Such White House antics display a tempting show of weakness to America's adversaries, inviting them to test the president's ability to respond. (Trump's minor missile strike on one Syrian base is no longer viewed abroad as a sign of strength.)

Trump is eager to withdraw from the nuclear treaty with Iran (over Tillerson's disapproval), and chafing over North Korea's missile testing. But can the country trust the reaction of an erratic president who tweets before consulting his experts, and believes he knows better than his generals?

Trump's next missile strike might heedlessly trigger a war.

Which brings me back to McCain's warnings. "We are an important check on the powers of the executive," he told his fellow legislators. "Our consent is necessary" for key appointments and "in many respects to conduct foreign policy. We are not the president's subordinates. We are his equal!"

What this means is that it is insufficient for the Senate to resume bipartisan cooperation on legislation (although it would be a welcome miracle if this happened).

It's time for a bipartisan delegation of senators to visit the White House and warn Trump that his destructive style of governance is endangering the country and emboldening bad guys. McCain understands this, but he can't do it alone (or with the two brave female GOP senators who voted nay on the Trumpcare horror).

Which male GOP senators, if any, have the guts to follow his lead?