Will this Donald Trump pivot stick?

Donald Trump has demonstrated more than once that he can project a more disciplined and presidential style when he wants, only to quickly slip back to his old ways.

His first address to Congress was widely seen as a shift to a more presidential tone after a combative and chaotic first 40 days in office. But will it last?

A look at past Trump "pivots" that didn't last long, from the man who once promised as a candidate: "I will be so presidential that you'll call me and you'll say, 'Donald, you have to stop that, it's too much.'"

INAUGURATION
Trump's team promised the new president would deliver a visionary and optimistic inaugural address laying out a unified path forward for a divided nation. Trump did manage to hew to a disciplined script for his 16-minute address, and he followed that up with a gracious declaration of respect for campaign rival Hillary Clinton during a post-inaugural luncheon. But Trump's address had a darker tone than expected, sketching a nation in the throes of ``American carnage.'' And the next day, when he was supposed to make a bridge-building visit to the CIA, he veered wildly off topic to complain at length that the news media had low-balled turnout estimates for his inauguration. This happened as he stood in front of a memorial to fallen CIA officers.

ELECTION NIGHT
Trump's election-night victory speech was a call to ``bind the wounds of division'' and "come together as one united people" after a rancorous campaign in which he urged on supporters as they chanted "lock her up" about Democratic rival Hillary Clinton, whom he labeled a "nasty woman." Trump said the nation owed Clinton "a major debt of gratitude" for public service. He pledged to be a president for all Americans and told those who opposed him that "I'm reaching out to you for your guidance and your help so that we can work together and unify our great country."

Soon enough, though, Trump was back to his combative self, firing off angry tweets about everything from "Saturday Night Live" to the play "Hamilton." Trump's presidential transition period featured very public spats with U.S. intelligence agencies, Clinton, Meryl Streep and civil rights hero Rep. John Lewis, D-Ga.

CONVENTIONAL MOMENT
Trump delivered a confident, albeit dark, GOP convention speech in which he declared that he alone could fix what ails the nation. "I have joined the political arena so that the powerful can no longer beat up on people that cannot defend themselves," Trump declared.

The next morning, when he should have been taking a feel-good victory lap, Trump chose to rehash past ugly battles with primary rival Ted Cruz. He defended his decision to retweet an unflattering photo of Cruz's wife, Heidi, and revived unfounded speculation about Cruz's father's possible links to the assassination of President John F. Kennedy. He also declared that he would never accept the Texas senator's backing and accused Cruz of a "dishonourable" failure to endorse him at the convention. In ensuing weeks, he lobbed sustained criticism at a Pakistani-American family whose son was killed while fighting for the U.S. in Iraq and warned that the November election results could be rigged.

JUDGE NOT
Trump used a primary-night victory speech in June to reassure Republicans that he could rein in his caustic and divisive attacks after he had worried party leaders by repeatedly questioning whether a federal judge of Mexican heritage could fairly preside over a case involving a Trump business. "I understand the responsibility of carrying the mantle" of the Republican Party, Trump promised in his speech, making rare use of a teleprompter. "I will never, ever let you down."

Within days, though, Trump was back in a combative mode, calling Sen. Elizabeth Warren "Pocahontas" and "goofy" on Twitter. He had strong words for Republicans, too, complaining that many in the GOP had been too slow to back him and deriding past Republican nominee Mitt Romney as a "sad case" who "choked like a dog." His rhetoric dashed hopes by many in the party that Trump would keep his focus on Clinton.

As Trump had said at a prior news conference: "You think I'm going to change? I'm not changing."