Donald Trump faces high stakes Monday — and possible political peril — with a much-touted speech criticizing Hillary Clinton's candidacy that will now also serve as his first public address since Sunday's deadly terror attack in Orlando.

"Mr. Trump's message isn't entirely about being tough, it's about being smart, vigilant and talking about the difficult subjects in order to produce common sense solutions for all Americans,” Trump campaign manager Corey Lewandowski told NBC News in a preview of what to expect from the speech which the candidate will deliver at St. Anselm College in Manchester, New Hampshire.

"Mr. Trump is tough on terrorism because there should be no other option when it comes to the threats we face to our safety and freedoms. He is a leader for all and his message today emphasizes that."

The speech comes at a pivotal time for the candidate, who has seen Republican critics grow louder — and talk of a contested convention coup reignite — in the wake of his racially-charged criticism of a federal judge and multiple reports outlining his lack of a campaign infrastructure.

Ian Prior, Communications Director for the major GOP super PAC American Crossroads, said Trump could turn things around with the speech.

“His opportunity here is to essentially re-set and re-define the race, not just define Hillary but define Trump vs. Hillary,” he said.

Trump’s advisers had hoped the speech would do just that — refocus the general election narrative as one of contrasts between their candidate and Clinton, and offer a roadmap for the general election.

But in the wake of the Orlando shooting, the campaign alerted reporters that Trump’s speech would “further address this terrorist attack, immigration, and national security.”

RELATED: What We Know About the Orlando Terror Attack

It’s a shift in focus that his aides believe still leaves ample opportunity to draw those differences with Clinton, but it’s a risky one, as it drives Trump back into some of the issues that have caused him the most controversy over the course of his campaign.

Trump’s Muslim ban proposal has been almost universally rejected by GOP leaders, and Trump himself seemed to begin to walk it back in recent weeks. But on Sunday, he issued a tweet reiterating his support for the idea.

"What has happened in Orlando is just the beginning. Our leadership is weak and ineffective. I called it and asked for the ban. Must be tough,” he tweeted.

What has happened in Orlando is just the beginning. Our leadership is weak and ineffective. I called it and asked for the ban. Must be tough — Donald J. Trump (@realDonaldTrump) June 12, 2016

Party operatives had hoped Trump would remain silent on the attacks so as not to politicize the tragedy in Orlando. Those hoping for a change in tone from the presumptive GOP nominee, however, were likely disappointed by a tweet Trump sent Sunday thanking supporters for “congratulating” him for being right.

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Appreciate the congrats for being right on radical Islamic terrorism, I don't want congrats, I want toughness & vigilance. We must be smart! — Donald J. Trump (@realDonaldTrump) June 12, 2016

In a sign of how divided the party remains, an aide to GOP New Hampshire Sen. Kelly Ayotte confirmed she would not attend the speech, or a planned Trump rally in the state Monday before the rally was canceled in the wake of the shootings.

Though her office has said she still supports Trump, she’s privately expressed frustration to Republican leaders over his racially-charged criticism of a judge overseeing a lawsuit against Trump University With a tough re-election fight looming an appearance with Trump could further hurt her chances.

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Trump, meanwhile, has a tough case to make on national security, as polling suggests Americans see Clinton as better-equipped to handle the issue. The latest NBC News/Wall Street Journal poll, released last week, showed Clinton with a nearly 30 point advantage over Trump when registered voters were asked which candidate would be better at handling foreign policy.

Clinton sought to solidify that advantage with a speech on June 2 painting Trump as dangerously unpredictable and inexperienced on foreign policy, and she’s likely to hit those themes again with a Monday speech her aides say will address the terrorist attack while also criticizing Trump.

Still, Republicans believe national security and terrorism can be a winning issue for their party, as they see Clinton's tenure as Secretary of State rife with missed opportunities and abject failures of leadership. "Republicans are the party which champions America’s centuries-old track record of peace through strength," RNC communications director Sean Spicer told NBC News. "We have a more clear-eyed and honest assessment of the global threats to America than Democrats, who bury their head in the sand on how dangerous the world is."

And Colin Reed, Executive Director of America Rising, the major GOP opposition research group that’s been digging into Clinton’s record for years, said that “any way you slice it her record at State was abysmal.

“There not a corner of her world that’s better off as a result of her tenure at State,” he added, noting in particular her attempt at a reset in relations with Russia, the ongoing chaos in Libya and her past praise of Syrian President Bashar al-Assad.

And a terrorist attack on U.S. soil that killed 50 people, making it the deadliest shooting in the nation’s history, could cause backlash against the party controlling the White House and raise doubts about Democrats’ ability to handle national security risks.

RELATED: Clinton Releases First General Election Ad Against Trump

The key, Republican operatives acknowledge, is for Trump to appeal to those skeptics with a serious, focused speech highlighting Clinton’s failures in contrast to his own vision for leadership — not just firing off his typical stump-speech lines.

“He needs to do it in a way that turns his weaknesses into strengths, highlights his strengths and goes after her in a smart way,” Prior, the super PAC strategist, said.

“He needs to pick his spots, though, where he gets snarky. It can’t be, ‘She’s going to jail!’ It needs to be more substantive than that and more thought-out than he’s been so far.”

Trump has a small circle of advisers that are helping him to develop the substance of the speech, which includes daughter Ivanka, her husband Jared Kushner and top campaign advisers Paul Manafort, Lewandowski, policy adviser Stephen Miller and his transition team chair, New Jersey Gov. Chris Christie.

Miller, sources tell NBC News, frequently writes the first draft of Trump’s speeches, and often previews the candidate’s lines when warming up the crowd for him at rallies.

At Trump’s Richmond, Va. rally on Friday, Miller seemed to hint at the contrast Trump could draw on Monday when he told the crowd the coming election was about “civilization,” and whether the “leader of the western world and free world sell out the country for a little extra campaign cash.”

Trump’s been hammering that same theme — that Clinton is “crooked” — and on Friday tied that argument to another favorite line of attack, her use of a private email server.

“Hillary Clinton has jeopardized--totally jeopardized--national security by putting her emails on a private server, all to hide her corrupt dealings,” he told the audience at a gathering hosted by the Faith and Freedom Coalition, expanding on his usual charge that Clinton’s email use shows “bad judgment.”

Trump’s also hammered Clinton for the attacks on Benghazi under her watch; what he says is her support for a “500 percent increase in Syrian refugees to come into our country”; the “mess she’s got us into with Syria”; and declared earlier this month in California that “she's not respected by other countries.”

“Her Libya invasion, decisions on Syria, Iraq, and Iran have made the Middle East more dangerous than ever,” he said that same week, also on the stump in California.

Taken together, Trump’s criticisms of Clinton amount to painting her as a “weak person” with “bad judgment” who’s unfit to lead the nation.

“Hillary Clinton is a thief and Hillary Clinton should be in jail for what she did to our national security,” he said in California.

Republican operatives say Trump’s hit on the right points, and that he needs more focus in his critiques. But they acknowledge they’ve been burned by Trump before, as recently as his press conference announcing his donations to veterans’ charities earlier this month. Then, advisers planned remarks in which Trump would raise issues like Benghazi and the Bowe Bergdahl swap against Clinton, but he went entirely off-script and unleashed a tirade against the press.

Still, with Clinton opening a steady lead over Trump just over a month out from the Republican National Convention, all Republicans can do is hope for Trump to get it right.

"There’s nothing that’s going to reset [the narrative] other than the candidate himself,” one operative said, warning that the "outrageous things he’s said are going to have a longer lifespan than they did during the primary season.”

NBC News' Kelly O'Donnell contributed to this report.