Donald Trump and Jeb Bush visited the U.S.-Mexico border a month apart.

Although Trump's visit came with throngs of television cameras and reporters, Bush's was much more low-key on Monday.

The contrast was illustrative of the approaches to their presidential campaigns: Trump, the brash and unpredictable front-runner, Bush, who ceded that top status to Trump, more methodical. And in recent days, they have sparred on substance too, particularly over immigration

President Obama thinks that picking Joe Biden to serve as his vice president is the best decision he ever made, but he's not endorsing Biden in a race to succeed him. He has made many "warm" comments about Hillary Rodham Clinton's performance as his secretary of State too, but he's not endorsing her either.

At this point, White House Press Secretary Josh Earnest says he won't speculate about whether the president will endorse anyone at all in the Democratic primary. But neither would he rule an endorsement out.

Such is the perilous line the White House is treading as Biden contemplates a late entry into the race for the Democratic nomination against Clinton, setting up a possible family fight that would put the sitting president square in the middle.

It's far from a done deal that Biden will jump in the race. He would have big obstacles to surmount, such as trying to enlist donors months after Clinton started locking down commitments from fellow Democrats.

But Biden can claim credit for many of the Obama administration's successes. Earnest acknowledged as much Monday, returning to the White House briefing room after a two-week break during Obama's summer vacation to fend off a backlog of questions about which top advisor Obama would prefer to see as the Democratic nominee in 2016.

"There is so much that has been accomplished over the last six or seven years that President Obama is enormously proud of," Earnest said, "and a large portion of it would not have been possible without the wisdom, counsel and leadership of Vice President Biden."

Then again, he said, "the president has spoken at quite some length about the appreciation, respect and admiration he has for the service of Secretary Clinton, particularly in her four years as secretary of State."

"Just not his best decision," observed a reporter.

"All of you and -- and your coverage of some of the president's comments about Secretary Clinton -- have noted how warm those comments were," Earnest quickly replied.

The awkward doublespeak could go on for a while. Biden aides have said he'll make a decision about running by the end of summer (a period Earnest noted Monday could last another month). The first Democratic debate is Oct. 13.

Obama and Biden were lunching at the time of the briefing, but Earnest indicated he'd give no hints afterward about what they talked about.

"Let me just put all my cards on the table here," Earnest said, before promising to do exactly the opposite. "I am not going to be in the position of confirming individual meetings that the vice president participates in."

The Jeb Bush campaign knew this was coming.

Back in April 2013, former First Lady Barbara Bush delivered the ultimate in harsh motherly advice when she told her second son, via the "Today" show , that she didn't think he should run for president.

The Bush family matriarch's explanation was couched in some kind words -- "He's by far the best-qualified man" -- but it was still blunt and candid and damaging in a way only a mom can be.

Having decided to ignore mom's advice, Jeb Bush has tried to neutralize the "enough Bushes" comment in many ways. Barbara Bush has repeatedly said she's changed her mind. Jeb Bush has made light of the comment and his mother's candor has become a running joke in the campaign.

Still, it didn't take long for a rival to use Barbara Bush's comment against her son. And it is not surprising which rival it is.

Will worries on Wall Street send voters over to a billionaire candidate who claims to have the Midas touch? Donald Trump made the case as the market fell Monday morning.

At every campaign stop, Jeb Bush promises to restore economic growth to 4% a year using the skills he demonstrated as Florida governor. The Times' Noah Bierman takes a close look at that Bush's record as economic steward during his tenure in Florida.

Bierman zooms in a project Bush initiated to lure the biotech industry to Florida. The Scripps Initiative involved hundreds of millions of dollars in state subsidies, but more than a decade later it's failed to deliver.

Bierman notes it's the type of project that probably wouldn't fly in the post-tea party GOP:

"Yet even among incentive plans, this one was unusual. Typically, states build a new highway ramp or offer tax abatement or some other break to lure a company. Bush offered cash, mostly post-Sept. 11 federal stimulus money approved by his brother, then-President George W. Bush. ... Legislators' easy embrace of the project is a reminder of how much the Republican Party has changed since Bush left the governor's mansion in January 2007. The rise of the tea party, partly in reaction to the increase in government spending under his brother's presidency, has created a sizable swath of the GOP electorate that opposes such large-scale subsidies."