'Start Here': Brexit vote postponed, Pelosi and Schumer to meet with Trump, deceptive 'deepfakes.' What you need to know to start your day. Prime Minister Theresa May is searching for support to follow through on Brexit.

It's Tuesday, Dec. 11, 2018. Thanks for choosing to start here.

1. Theresa May calls off key Brexit vote

British Prime Minister Theresa May delayed Tuesday's key vote in Parliament on Brexit after she admitted the deal "would be rejected by a significant margin."

May told members of Parliament she would seek "assurances" from the European Union this week over the deal's backstop arrangement, but she continued to defend the withdrawal agreement, adding she believed she could secure a majority vote.

ABC News Senior Foreign Correspondent Ian Pannell tells us it's been a long and painful process: "It's easy to oppose something, but what do you put in its place?"

2. Schumer, Pelosi to meet with Trump

In 2017, when Chuck Schumer and Nancy Pelosi went into the White House, they walked out with what they said was an agreement with President Donald Trump. That agreement never materialized after both sides accused the other of lying.

Today, Pelosi and Schumer are heading back to the White House to avert a partial government shutdown.

ABC News Deputy Political Director MaryAlice Parks tells us Pelosi also is contending with some loud voices within her own party demanding term limits and what activists call a "Green New Deal."

3. Accused Russian agent Maria Butina agrees to plea deal

Maria Butina, a Russian gun-rights activist accused of being a Kremlin agent, is expected to plead guilty to conspiracy and cooperate with federal, state and local authorities in ongoing investigations.

Federal prosecutors have alleged that Butina worked with a Russian government official to develop a covert influence operation, establishing contacts with conservative political operatives and the National Rifle Association to push Moscow's agenda.

She's scheduled to appear in court on Wednesday.

"If the federal prosecutors are right, and Maria Butina was in fact a foreign agent operating in the United States," ABC News' Aaron Katersky tells us, "it's more evidence that the Russians were trying to make inroads through whatever political group they could."

4. Detecting 'deepfakes'

The president's constant crowing, without evidence, of the proliferation of "fake news" may actually turn out to be nothing compared to the actual fake news contained within "deepfakes."

Experts now fear that videos, created using artificial intelligence to convert or mutate real footage into footage where people are saying or doing things they really didn't, could lead to enormous real-life consequences.

"They're worried that it could influence an election -- that a video could get out there, a 'deepfake,' and all of a sudden people freak out and they change the way they vote," ABC News' Kyra Phillips tells us.

Other news:

'This thing may have just saved your life': An otherwise healthy 46-year-old man learns from his Apple Watch that he has a heart condition.

'An absolute joy to have in the dropzone': A 102-year-old Australian woman becomes the world's oldest skydiver.

'It's good to see the Trump administration paying attention to human rights abuses somewhere': The U.S. sanctions three North Korean officials.

Opening up about speaking out: American hero Aly Raisman describes her journey to becoming an advocate for survivors of sexual abuse.

Keeping it 100: Firefighters in Texas over the weekend saved more than 100 snakes from a house fire.

From our partners at FiveThirtyEight:

A Weird NFL Weekend Leaves Us Even More Confused

Last 'Nightline':

Family transforms home into larger-than-life North Pole Christmas display: ABC's "The Great Christmas Light Fight" showcases the elaborate displays families put up for the holidays, including the incredible show from the Mure family in Rockaway Beach, New York.

6:16

When seeing isn't believing: Using AI to create 'deepfakes': The latest in artificial intelligence allows creators to swap and meld videos, creating fun camera filters but also fake news footage.

8:08

Today in history:

Dec. 11, 1998 -- The House votes to impeach President Bill Clinton.

2:46

The must-see photo:

Snow-covered roads slowed traffic on I-85 in Lexington, North Carolina. (photo credit: H. Scott Hoffmann/News and Record/AP)

For more great photos from around the world click HERE.

Socially acceptable:

A cat was rescued after being stuck between walls for hours.

0:49

All right, you're off and running. You can always get the latest news on ABCNews.com and on the ABC News app. Details on how to subscribe to the "Start Here" podcast are below. See you tomorrow.

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