President Donald Trump at a news conference in the East...

President Donald Trump at a news conference in the East Room of the White House in Washington, Thursday, Sept. 7, 2017. Credit: AP

Nobody should be surprised that Republican President Donald Trump would side with Democrats when the moment suited him.

The positive bottom line is that the next Congressional debt-ceiling fight gets put off for three months, with emergency flood funding extended.

This isn’t exactly the Treaty of Westphalia. But it does mark the president’s first move of the kind since taking office.

For Trump, party loyalty always seems to work one way. Fans liked what they perceived as his “independence.”

Long before all the “Crooked Hillary” sneers, Trump was a Democrat who contributed to the coffers of both Bill Clinton and Hillary Clinton.

He also backed Sen. Charles Schumer — years before mocking him as a “crying clown.” Last Wednesday, the president amiably called him “Chuck” and referred to GOP-averse Minority Leader Nancy Pelosi by her first name too.

On the campaign trail, Trump derided the previous three Republican presidential nominees as losers.

Early in the GOP primaries, he balked at signing a pledge to back the eventual nominee. Then he agreed to it. Later he backed off, saying “We’ll see who it is.”

More substantially, Trump never signed on to the canon of fiscal conservatives who saw cuts in major entitlements and borrowing as key to budget balance and economic gain.

Last year, he suggested renegotiating the nation’s debt and said when asked how it might work: “You go back and you say, hey guess what, the economy crashed. I’m going to give you back half.”

All situations are perishable, week to week, on any “reality” show.

Leaders of the Republican majority in both congressional houses were reportedly “shellshocked” and “visibly annoyed” when Trump sided with the Democratic leaders in a meeting.

What they expected instead is unclear, given their recent tensions with the White House.

The GOP in Congress will be looking to midterm elections next year. When hard-line conservative members campaign, perhaps they’ll fault the president for straying from the mission.

Or maybe circumstances will change next week and Trump will start blaming Democrats again for obstruction.

Or maybe Trump’s detente will somehow help clear the way for Republican leaders to begin addressing other priorities.

Trying to look ahead can be tricky in Trump’s world.

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