'Start Here': Mueller to testify before Congress, acting border chief steps down, Dem debates begin Here's what you need to know to start your day.

It's Wednesday, June 26, 2019. Let's start here.

1. Must-see Mueller TV

Special counsel Robert Mueller has agreed to testify publicly before Congress about the Russia investigation on July 17 after he was subpoenaed by two House committees.

"Americans have demanded to hear directly from the Special Counsel so they can understand what he and his team examined, uncovered, and determined about Russia's attack on our democracy, the Trump campaign's acceptance and use of that help, and President Trump and his associates' obstruction of the investigation into that attack," House Judiciary Committee Chairman Jerry Nadler, D-N.Y., and House Intelligence Committee Chairman Adam Schiff, D-Calif., said in a joint statement on Tuesday night.

Mueller said in a public statement weeks ago that he had no further plans to speak publicly on the Russia probe. He was wary of creating a political spectacle, according to ABC News Senior Congressional Correspondent Mary Bruce, who says Democrats have been eager for a "big, show-stopping hearing."

"There are plenty of questions that lawmakers have for him," she says on "Start Here." "What remains unknown is how much he's going to answer because he made pretty clear that his report, he says, speaks for itself."

In response to the news of Mueller's upcoming testimony, Jay Sekulow, President Donald Trump's lead attorney, told ABC News: "Bob Mueller agreed to testify. He already said his testimony will be his report. We expect his testimony will be the report."

2. Border chief resigns

Acting U.S. Customs and Border Protection Commissioner John Sanders is stepping down after two months on the job amid growing scrutiny over the conditions at immigrant detention facilities. Immigration and Customs Enforcement's acting head, Mark Morgan, has been tapped to replace him, according to a government official.

Sources told ABC News Sanders' resignation "had nothing to do" with reports that a Texas border holding facility housed migrant children in conditions one doctor compared to "torture facilities."

"These are where kids are being housed, apparently sleeping on concrete floors with Mylar blankets, something I've seen myself," ABC News Chief National Correspondent Matt Gutman says. "Apparently they're also being denied basic hygienic products like soap and toothbrushes and toothpaste."

The CBP said in a statement it's leveraging its resources to "provide the best care possible to those in our custody, especially children," adding, "all allegations of civil rights abuses or mistreatment in CBP detention are taken seriously and investigated to the fullest extent possible."

3. Welcome to Miami

The first round of Democratic presidential candidates are gathering in Miami for debate night with hopes of convincing voters they have what it takes to beat Trump in 2020.

It's also an opportunity for some of the lower-polling candidates to stand out from the crowd and maybe even take on the current front-runner, former Vice President Joe Biden, according to ABC News Chief Political Analyst Matthew Dowd, who offers some advice for Sen. Elizabeth Warren, D-Mass., on "Start Here."

"Elizabeth Warren, more than any other candidate in the last month, has been on the rise ... because of her ability to have an answer or some policy prescription for everything," he says. "I would just say, just keep doing what you've done on the trail ... what's gotten her to this point where she's now competing with Bernie Sanders for second place."

4. 'Obliteration'

The president ramped up the rhetoric in a war of words with Iran on Tuesday, threatening the country with "obliteration" if Iranians engaged in an attack, after Tehran said the White House "is afflicted by mental retardation."

"Despite the president and some of his top officials continuing to say that they want Iran to come to the table, that tweet signals that the U.S. is still prepared to respond," ABC News' Elizabeth McLaughlin says.

As Trump heads to the G-20 summit in Japan today, new acting Secretary of Defense Mark Esper will be making an appeal to NATO allies for help in supporting the administration's "maximum pressure" campaign against Iran.

But, McLaughlin adds, it may be a tough sell: "The problem here is that a lot of those countries are going to see the U.S. argument as kind of hollow. The U.S. was the one who reneged on the Iran deal."

"Start Here," ABC News' flagship podcast, offers a straightforward look at the day's top stories in 20 minutes. Listen for free every weekday on Apple Podcasts, Google Podcasts, iHeartRadio, Spotify, Stitcher, TuneIn or the ABC News app. Follow @StartHereABC on Twitter, Facebook and Instagram for exclusive content and show updates.

Elsewhere:

'Clandestine operations': India and Pakistan are still squabbling over $45 million tucked away in a London bank in 1947.

'It was very apparent that he wanted a relationship with her': A man rejected by a woman is accused of retaliating by shooting her 10-month-old girl in the head.

'Foodie call': Women who go on dates solely for the free meals are more likely to be psychos, according to science.

From our friends at FiveThirtyEight:

Where Democrats and Republicans live in your city: They tend not to live side-by-side, even when they live in the same city.

Doff your cap:

A tough-as-nails Pennsylvania great-grandmother is being heralded by her neighbors after she used a shovel to kill a cobra in her backyard.

Falls Township resident Kathy Kehoe, 73, suspected something was wrong when she heard blue jays near her home squawking frantically, she told ABC Philadelphia station WPVI.

"I knew right away," it was a snake, she said.

She realized she was dealing with a cobra after she nudged the reptile's tail, prompting it to rise up and spread its hood. It measured 4 to 5 feet, she said.

Kehoe's neighbors sung her praises in dispatching with the snake.

"She's a bada--," Alise Kaplan told WPVI, adding it's "incredibly scary" a cobra was loose nearby.