Washington (CNN) One of the most remarkable moments on the campaign trail this week was one that didn't happen.

Former Miss Universe Alicia Machado introduced Hillary Clinton at a Florida rally Tuesday, blasting Donald Trump.

And for once, the billionaire didn't react. No tweets. No attacks from the stump. Nothing. Instead, he stayed on message going after Clinton on her email server while pledging to repeal Obamacare.

In the final days of the 2016 campaign, Trump isn't taking Clinton's bait.

The new self-discipline comes as the election tightens and polls indicate a razor-close race in battleground states such as Florida, New Hampshire and Colorado. On the stump Wednesday night in Florida, Trump revealed how he is focused on staying disciplined and how hard it is for him.

He talked to himself out loud on the stump: "We've got to be nice and cool, nice and cool, right? Stay on point, Donald, stay on point. No side tracks Donald. Nice and easy."

For months, when the campaign narrative wasn't going Clinton's way or polls were tightening, all her team had to do was go after their Republican rival on something that hit him close to home. He reliably reacted by lashing out in a way that caused a firestorm and then -- boom -- the discussion was back where Clinton advisers wanted it: all about Trump.

It's a strategy that exceeded the Clinton campaign's wildest dreams at the Democratic convention, where they gave Gold Star parents Khizr and Ghazala Khan prime-time speaking slots attacking Trump. That prompted an angry response from Trump that drew criticism from fellow Republicans -- and dominated the news cycle for days.

Rinse and repeat

After that, it was rinse and repeat for the Clinton campaign.

Their biggest success was the way Trump reacted to Clinton ending the first debate, when she highlighted his past comments about Machado. He not only ranted about it at events, he went after Machado personally, including an especially odd tweet sent at 3 am suggesting she had a sex tape.

Clinton was quite transparent about her strategy, tweeting, "a man you can bait with a tweet is not a man we can trust with nuclear weapons."

Throughout Trump's entire White House run, the biggest frustration among members of his campaign team -- and one of the reasons he went through three campaign managers -- has been that his advisers couldn't control him and therefore couldn't control the message of his campaign.

And it's not as if they didn't try. They did, but Trump didn't listen.

"Up until a week ago, he would say 'I hear you, I get it. But you're wrong,' " said one source close to Trump, who described his attempts for months to get him to stay on message.

This source says Trump's refrain in private was that's what makes him different -- people view him as real, even if he is off the mark sometimes.

Why the change?

But now, the GOP nominee is suddenly showing remarkable discipline. He is restraining himself on Twitter and is largely sticking to script during speeches at rallies.

So where did Teleprompter Trump come from? What changed? There are several answers, according multiple sources close to Trump.

One is what a Trump confidante called a "thunderbolt from God" -- the bombshell news from FBI Director Jim Comey that the agency is reexamining emails potentially tied to Clinton's private server.

That gave Trump a reason to focus where he should -- on his political opponent. It also gave him hope that he actually could win, especially since even before news of the review surfaced, Trump's advisers were showing him data suggesting polls were narrowing in some must-win battleground states.

That's heightened with new polls in battleground states such as Florida and North Carolina showing razor-thin races.

Another change is the calendar. Trump knows it's almost over. He is telling those close to him that he realizes he has been in the "red zone," but now -- using a football analogy -- he can see the "end zone."

A different Trump source used a baseball analogy to describe Trump and why he is exhibiting the self-control many thought he didn't have.

"He is a closer," said this Trump source, who also called him a "big game player."

And then there is the company he is keeping on the campaign trail. Sources say, Jared Kushner, who is married to Trump's daughter, Ivanka, has been traveling more often with Trump. Kushner has long been an instrumental behind-the-scenes force in Trump's campaign and GOP sources tell CNN his presence recently on the trail has helped keep Trump in check.

Same goes for Steve Bannon, a top Trump campaign official on leave from the conservative Breitbart. Bannon is also now a regular presence on the plane with Trump -- which sources say is aimed at keeping the candidate focused.

Republican National Committee chair Reince Priebus is another force with Trump often pushing him to stay on message.

Another source tells CNN what Trump's trusted traveling advisers do now is encourage him to get his frustration, anger or off-script thoughts out of his system before he gets on stage.

Republicans say Trump's self-control directly affects poll numbers

During the primaries, Trump always spoke off the cuff in his speeches and regularly mocked Clinton for using a Teleprompter in her speeches. But after one too many self-inflicted wounds, he gave into the entreaties of advisers to use one himself.

He didn't stick with it -- not even close. And it usually got him into trouble.

It was not really until recently when things started moving his way. The government reported Obamacare premiums will go up next year, and the surprise FBI announcement its investigation of Clinton emails isn't over gave Trump an unexpected opening.

The bang-their-head-against-the-wall exasperation Republicans experience when Trump goes rogue stems from the direct correlation they see in his off-message mishaps and the poll numbers for his campaign -- not to mention as down-ballot Republicans.

"When Mr. Trump stays on message, people come home real quick," said RNC Chief of Staff Katie Walsh, speaking to Kevin Madden and Mary Katherine Ham on their "Party People" podcast.

But when the news cycle is all about Trump -- often things he said or did to offend people -- GOP strategists say they saw many vulnerable Senate and House candidates take a hit in the polls.

"When Donald Trump sticks to the script and reads from a Teleprompter, like he did in September and like he is doing this week, we see a bump in polling for down ballot races," said Mike Shields, a CNN contributor who runs the Congressional Leadership Fund, the primary super PAC for House Republican leaders aimed at maintaining their majority.

"If the election is about Hillary, everyone on the ticket does better. If the election is about Trump, everyone on the ticket does worse," Shields added.

Last month's release of the 2005 "Access Hollywood" tape depicting Trump lewdly talking about what he does to women was one of the low points for Republicans watching House races. The tape had such a negative effect on other GOP candidates that Republicans started to worry Democrats might be about to find the 30 seats they need to flip in order to re-take control of the House.

It got even worse when women started to allege that Trump had groped them, and he lashed out -- even stepping on what aides had previewed as a key policy address in Gettysburg, Pennsylvania.

In an interview a few days after that incident, Trump campaign manager Kellyanne Conway told CNN she made clear to Trump she thought that was a mistake on his plane following that event, telling him that he sounds like he is going to lose.

In public, Conway's not-so-subtle refrain was that her candidate is at his best when he is talking about the issues, as opposed to controversies swirling around him or his campaign. But even in the face of evidence that his lack of self-control often causes his campaign to spiral downward, Trump seemed impervious to pleas from his advisers to stop.

Sources close to the GOP nominee concede his brash responses often made it seem that Trump simply couldn't stay on message and was inherently unable to let a slight or attack go -- even if it meant hurting his own campaign.

Yet for almost a week, Trump has shown he is in fact capable of being disciplined. Luckily for Trump's battle-worn advisers, it's a lot easier to get him to that place when the focus of the campaign is on his opponent's problems -- and not his.

But, they concede, there is still time -- lots of time -- for Teleprompter Trump to revert to Rogue Trump before next Tuesday.