First Read is a morning briefing from Meet the Press and the NBC Political Unit on the day's most important political stories and why they matter.

The Unity Gap: Democrats appear to be uniting in a more orderly manner than Republicans are

No one is 100% sure how President Obama’s meeting with Bernie Sanders will go at 11:15 am ET at the White House, but it sure seems like Democrats are unifying in a more orderly manner than Republicans are. After he meets with the president, Sanders huddles with Senate Minority Leader Harry Reid at 2:00 pm ET.

Note this dispatch from NBC’s Chris Jansing: “[Last night], Bernie Sanders called members of his senior staff and longtime aides to his house for a meeting that included Jeff Weaver, Tad Devine, Michael Briggs, Shannon Jackson and others. He's now said to be in a positive frame of mind and focused on Thursday's meetings -- some of the good feeling apparently motivated … by Biden's ‘we should be graceful’ [comment], but I also got a very positive reaction to [Obama’s remarks to Jimmy Fallon] giving Sanders props for bringing ‘new ideas’ and tremendous energy to the campaign.”

As we wrote earlier this week, WWBD -- What Will Bernie Do? -- is one of the most important storylines for Democrats this summer. But the early signs suggest that this is playing out exactly how Obama and Hillary Clinton want it to play out. What to watch for: Will the upcoming polls show Clinton consolidating the Democratic vote?

Sen. Susan Collins: “I've never even met Donald Trump”

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By contrast, you have the Republican uproar over Donald Trump’s attacks on federal judge Gonzalo Curiel. Check out what moderate Sen. Susan Collins (R-ME) said on MSNBC’s “MTP Daily” about Trump: "I do believe that Mr. Trump does still have time to right the ship, to start acting presidential, and to focus on the economy, where I believe that his message resonates and he has some good ideas. And, if he does that, he may well win my support. If he doesn't, it's going to be very difficult for me to support him."

And when she was asked with whom she would have a working better relationship – Trump or Clinton – here was Collins’ response: “Let me say that I can't answer that, because I've never even met Donald Trump. I think it's odd that he hasn't come to speak to the Republican Senate caucus, but I've never even been in the same room with Donald Trump, whereas I do have a personal relationship with Hillary. We did work well together when she was in the Senate on causes like Alzheimer's disease. And, I worked with her when she was Secretary of State on the empowerment of Women in Afghanistan.” Interesting…

Let the veepstakes fun begin!

Now that we have presumptive presidential nominees for both parties, it’s time for the Veepstakes portion of the 2016 campaign to begin. This morning, NBC News has published cheat sheets on the VP frontrunners for Hillary Clinton (Sherrod Brown, Julian Castro, Tim Kaine, Amy Klobuchar, Tom Perez, and Elizabeth Warren) and for Donald Trump (Kelly Ayotte, Chris Christie, Bob Corker, Mary Fallin, Newt Gingrich, Rick Scott, Jeff Sessions, and John Thune).

Warren to rip Trump

In her address to the American Constitution Society’s national convention in DC tonight, Sen. Elizabeth Warren will blast Donald Trump over his criticism of federal judge Gonzalo Curiel -- and will link Trump to other Republican leaders like Senate Majority Leader Mitch McConnell and House Speaker Paul Ryan, according to excerpts of her remarks.

“Judge Curiel is one of countless American patriots who has spent decades quietly serving his country, sometimes at great risk to his own life," she will say. "Donald Trump is a loud, nasty, thin-skinned fraud who has never risked anything for anyone and serves nobody but himself. And that is just one of the many reasons why he will never be president of the United States.”

More from Warren: “Trump isn’t a different kind of candidate. He’s a Mitch McConnell kind of candidate. Exactly the kind of candidate you’d expect from a Republican Party whose ‘script’ for several years has been to execute a full-scale assault on the integrity of our courts."

And: “Trump is also House Speaker Paul Ryan’s kind of candidate. Paul Ryan condemned Trump’s campaign for its attacks on Judge Curiel’s integrity. Great. Where’s Paul Ryan’s condemnation of the blockade, the intimidation, the smears, and the slime against the integrity of qualified judicial nominees and Judge Garland?”

Our take: It sure seems like Warren is all in, and is embracing this VP tryout role.

Let the battleground campaigning begin!

On Friday, Donald Trump begins his general-election campaigning with a rally in Richmond, VA. On Saturday, he hits Tampa, FL and Pittsburgh, PA. And on Monday, Trump goes to Manchester, NH. Meanwhile, Hillary Clinton travels to Ohio on Monday and the Pittsburgh area on Tuesday.

On the trail

Hillary Clinton is down in Chappaqua, NY… And Donald Trump has a meeting with donors in New York. Don’t forget to check out the political unit’s rolling minute-to-minute coverage of all the latest 2016 developments at the On the Trail liveblog at NBCNews.com.