FILE - In this Aug. 23, 2017 file photo, President Donald Trump walks on the South Lawn of the White House in Washington. The president lashed out at Republican leaders in Congress, suggesting efforts to increase the country's borrowing limit to avoid an economic-rattling default on the nation's debt are "a mess!" (AP Photo/Carolyn Kaster)
FILE - In this Aug. 23, 2017 file photo, President Donald Trump walks on the South Lawn of the White House in Washington. The president lashed out at Republican leaders in Congress, suggesting efforts to increase the country's borrowing limit to avoid an economic-rattling default on the nation's debt are "a mess!" (AP Photo/Carolyn Kaster) Credit: Carolyn Kaster

Washington — Senate Majority Leader Mitch McConnell tends toward restraint in public comments, but his observation that President Donald Trump, as a newcomer to politics, had “excessive expectations” about the legislative process provoked an unexpected war with the White House that shows no signs of easing.

Trump, in tweet after scalding tweet, has turned on McConnell, attacking the Republican Senate leader — and at times House Speaker Paul Ryan — in a relentless barrage that continued on Thursday, long after each side’s offices had tried to put the matter to rest by pledging to work together on shared GOP priorities.

The outbursts from the president have not only driven a wedge between the White House and its Capitol Hill allies, they have also exposed the limits of the president’s understanding of how to interact with Congress and how the legislative branch works.

In many ways, Trump’s escalating retorts have only proven McConnell’s initial criticism correct.

This week, for example, Trump picked a fight with Congress over his proposed border wall with Mexico, threatening a government shutdown if lawmakers fail to provide construction funds, even though Trump once promised the money would come from Mexico. Though the wall was a key Trump campaign promise, it is not a priority for his party, particularly those who would rather cut government spending.

In recent weeks, Trump has started blaming the collapse of the GOP health care overhaul on “one vote” — referring to Sen. John McCain’s stunning dissent. In fact, the so-called “skinny” Obamacare repeal bill that McCain helped defeat was merely a placeholder for continued negotiations, and it remained highly uncertain whether the broader effort to repeal and replace the Affordable Care Act would have succeeded.

The president also has been pushing for elimination of the Senate filibuster, making it easier to pass legislation with a simple majority. But most senators from both parties resist that idea, preferring to preserve the Senate’s longstanding protection of minority views. Besides, top agenda items — health care and tax reform — can be accomplished under rules that only require 51 votes for passage.

On Thursday, Trump second-guessed GOP leaders’ plan for the debt limit battle, saying Congress should have linked that difficult vote to a popular Veterans Affairs bill that passed with overwhelming bipartisan support. Most view that idea as overly simplistic, saying such a maneuver more likely would have backfired and defeated both measures.

“I requested that Mitch M & Paul R tie the Debt Ceiling legislation into the popular V.A. Bill (which just passed) for easy approval. They … didn’t do it so now we have a big deal with Dems holding them up (as usual) on Debt Ceiling approval,” he tweeted. “Could have been so easy-now a mess!”

Trump appears to be unaware, or unconcerned, with the deepening divisions he is creating among the very leaders and lawmakers he will need to rely on for passage of the bills he wants to sign into law.