Why Donald Trump's poll numbers are surging right now

Donald Trump's surge in the polls isn't just the result of the usual bump presidential candidates historically enjoy after they sew up the primary battles and earn the "presumptive nominee" title. And it's also not just the result of Hillary Clinton's mistakes, even though she is making some serious campaign errors right now. What has been happening over the last few weeks is that Trump has changed his attack and messaging in a subtle but effective way, so subtle that many pundits may have missed it. But here are the three things Trump is doing very well right now:

1) He’s focusing much more on Hillary Clinton

A month ago, Trump was still talking and tweeting too much about the Republican opponents he had long since vanquished. But in the past week to 10 days, he's been much more focused on Clinton and that's had the dual effect of weakening her and persuading more and more reluctant Republicans to jump aboard the Trump train. But saying Trump is going after Clinton doesn't tell half the story; it's how he's attacking her that really matters.

First off, he's given her a new moniker that's sticking for a lot of the public: "Crooked Hillary." Trump no longer mentions Clinton on social media without that "Crooked" prefix. This was the same tactic that worked when he nailed Ted Cruz with the "Lyin' Ted" nickname and Jeb Bush with "Low Energy Jeb." A big part of successful campaigning involves quick and snappy sloganeering, and these nicknames have that in spades.

Secondly, Trump is hitting Clinton on a carefully selected array of issues that at one point or another will appeal to persuadable voters from all persuasions. For hard core gun rights voters, especially in the South, Trump has been calling Clinton an outright "gun grabber." For mainstream conservatives who focus on foreign policy, he's been reminding everyone of the mess in Syria and Libya that began during Clinton's term as Secretary of State.

For moderate-to-conservative women who aren't so sure Clinton deserves the women's vote just because she's a woman, Trump has continued to allude to her alleged complicity in Bill Clinton's sexual misconduct cases and for what Trump says is her relative silence about violent discrimination against women in the Muslim world.

And for progressive voters, Trump keeps reminding everyone of Clinton's ties to Wall Street and other alleged financial deals, thus the "Crooked" in "Crooked Hillary." These attacks seem to be leaving more of a mark on the Democratic frontrunner than they're helping Trump. In both the NBC News/Wall Street Journal and ABC News/Washington Post polls, Clinton's numbers are more down over the last month than Trump's numbers are up. That's the thing about effective negative campaigning, it doesn't boost your support that much, it just erodes your opponent's support more. But that's usually good enough to win.

2) He’s still brash, but in a different way

Before and during the primary contests, Trump stood out with loud and politically incorrect comments about illegal immigrants and Muslim visitors to the U.S. But now, that brashness is morphing into something a bit different. That was on full display last week when Trump basically blamed the EgyptAir crash on terrorism before most of the key facts came in. That's an entirely different kind of risky talk than bashing border security.

It was a gamble that seems to be paying off as all the proper experts now also say that terrorism is the most likely cause of the disaster. Trump getting well ahead of that part of the story would have made him look bad had the facts come out differently, but he saw it as a good bet to seem much more realistic and even forceful in a crisis. By contrast, Clinton and co. seem slow, and too politically correct to tell Americans the truth.

Trump has been similarly brash, but not so offensively brash, in his recent attacks on slow TSA security lines at airports. And the granddaddy of all perhaps premature, but still relatively safe, brash moves has been his decision to release his 11 top choices for Supreme Court justice. All of these moves present the voters with a specific idea of what a President Trump would sound like and even do. And while they are all a bit or a lot presumptuous in nature, they are much more plausible and popular than his earlier brashness on immigration and trade.

3) He’s bolstering Bernie

Trump hardly goes a day without saying or tweeting something in support of Bernie Sanders' uphill battle to win the Democratic nomination. Trump is repeatedly calling the process rigged against Sanders and generally unfair. This move accomplishes two things.

First, it keeps the heat on Clinton and potentially tires her out even more before she even gets a chance to solely focus on beating Trump. But secondly, and even more importantly, he's throwing an important line out to Bernie's supporters who are still very likely to be looking for another candidate in the coming months.

Trump probably has very little chance of winning a majority or even 40 percent of those soon-to-be-former Sanders voters. But any voters he gains from that camp would be a tremendous net gain. Just 20 percent of them could probably tip the scales for Trump decidedly given the fact that presently, Trump is still doing very poorly among the younger voters who so dominate the Sanders camp.

None of the above factors seems to be on the radar for Hillary Clinton's faltering campaign team. And as long as that's true, her numbers will continue to dwindle and Trump will surge on.

Commentary by Jake Novak, supervising producer of "Power Lunch." Follow him on Twitter @jakejakeny.

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