Since retired Marine Corps Gen. John Kelly started as White House chief of staff last month, President Donald Trump has added a routine caveat before approving proposals advisers place before him: Check with "The General" before moving ahead.

It's a marked departure from Trump's instinct to manage around Kelly's predecessor, Reince Priebus. When making a decision, one aide recalls, Trump often would caution, "Don't tell Reince."

Trump's appointment of Kelly has imposed new order on a White House that had been riven with infighting among warring camps. But it hasn't been the political lifeline Republican allies had hoped for, as Kelly has so far been unable to perform one of the chief of staff's most basic duties: to stop a president from following his worst instincts.

Trump's controversial initial response to the violence in Charlottesville, compounded by an off-the-cuff press conference days later and then defended again in a divisive, revisionist speech Tuesday in Phoenix, have laid bare the limits of Kelly's ability to manage his boss.

This month may be the most politically damaging so far of Trump's presidency, as the legitimacy he appeared to confer on white supremacists alienated allies in corporate America and antagonized Republican lawmakers. The ultimatum Trump issued Tuesday that he would shut down the federal government unless his fellow Republicans who control Congress pay for the border wall he promised compounds the challenges for Kelly ahead of the Sept. 30 funding deadline.

The respect aides say Trump has for Kelly, a decorated general, hasn't yet translated into deference when the president's passions run high.

In interviews with 14 current and former administration officials, congressional Republicans and people close to Trump and Kelly, most credited Kelly with imposing new processes and restrictions that have limited freelancing, drama, leaking and backbiting among staff. Kelly has strengthened chains of command and given Trump fewer distractions, clearing the path to execute decisions on everything from Stephen Bannon's departure to Afghanistan policy.

Kelly has implored Trump repeatedly to stay on script, emphasizing the importance of being precise and sensitive to the constituencies hearing his words. The president did stick to the text in his speech Monday night on his approach to Afghanistan. Beforehand, Kelly had emphasized the magnitude and somber nature of sending more young men and women into war.

"Gen. Kelly is an important voice in the administration and a straight shooter," Senate Majority Leader Mitch McConnell, a Kentucky Republican whose own tensions with Trump have been well documented, said in a statement. "He's been invaluable to the country throughout his career," McConnell said of Kelly, "and I appreciate him stepping up to serve in his new role."

One former Trump aide described a "Hunger Games" environment before Kelly came to the White House, between staff leaks and "insiders" selling access with claims of closeness to the president. "It's known those days are over," the aide said. "Everyone, including staff, knows it's a new day of structure and knows not to mess with Kelly."

Yet Trump still veers off message, from the response to the Virginia violence to social-media attacks on key members of his own party. His targets this month have included McConnell and senators Jeff Flake and Lindsey Graham.

Three current and former Trump aides, who spoke on condition of anonymity, said Kelly hasn't made a real dent on improving how Trump is viewed by the public, or in controlling negative news.

Another said that from the start of the presidency, Trump has been able to undo progress on executive orders or relationship building with Congress with a single tweet or an off-the-cuff remark, and that nothing has changed with Kelly's arrival except that with the departures of Priebus and Bannon, Trump now lacks people in the room who have the political instincts to channel the establishment or the base.

"With regard to the principal, I think the jury's still out on whether he can better discipline the president," said Leon Panetta, a former chief of staff to President Bill Clinton who later served as defense secretary and CIA director under President Barack Obama, and a supporter of Kelly, who served as Panetta's senior military aide at the Pentagon.

"Everybody that I've talked to feels a hell of a lot more comfortable with John Kelly in that job," Panetta said.

But the past two weeks have been "very damaging to the prestige and power of the office of the presidency. If I know John Kelly, he wants to be able to make sure the president is acting in the interests of the country," he added.

Panetta said Trump's apparent appetite for a government shutdown could be a key test for Kelly's ability to help Trump think through the long-term implications of his moves. "The chief of staff has to grab the president at a quiet moment and say, 'It's irresponsible,'" Panetta said. "It's bad for the economy, it's bad for the country, when that happens. And politically it can hurt the party."

Kelly's presence in the White House has been a source of reassurance to Republican lawmakers amid the recent political tumult.

One Capitol Hill Republican, who spoke on condition of anonymity, said it has been less than a month and that Kelly had been focused first on the things he could more easily address: getting the right processes and procedures in place at the White House in terms of staff, paperwork that reaches the president and traffic in and out of the Oval Office. "The change might not be that apparent yet," the Republican said.

One senior Republican congressional aide who is in regular contact with the White House said there is more confidence among lawmakers that Kelly is communicating their concerns in unvarnished terms to the president.

Another Senate Republican aide added, "Kelly is the only thing saving America right now."