An unusual campaign billboard popped up recently in the heart of Silicon Valley. It read, ‘Break up Big Tech’ with a large profile picture of Sen. Elizabeth Warren.

It is quickly becoming one of Warren’s signature campaign issues in her bid for the Democratic nomination in 2020. Her proposal calls for the government to break up Amazon, Google and Facebook, preventing them from competing on the internet platforms they own and operate.

“They want to be the umpire in the baseball game and they also want to run a bunch of teams in the game,” Warren said when she announced her plan.

Warren’s crusade is also starting to gain traction elsewhere on the campaign trail as well as inside the Beltway. Numerous Democratic presidential hopefuls are also now attacking big tech companies.

But even more significantly, Facebook, Google, Amazon and Apple are being investigated by both the House Judiciary Committee and Department of Justice for possible anti-trust activity.

Following Elizabeth Warren’s lead, Sen. Amy Klobuchar joined the call for government intervention to curb the power of the tech behemoths.

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“We are in fact in, not just heading into another Gilded Age,” the Minnesota lawmaker said March 5.

Kamala Harris is taking a more cautious approach, perhaps trying to have it both ways. The California Senator has held several big fundraisers in her tech-heavy backyard but then criticized big tech.

“There’s no question in my mind there needs to be serious regulation, that has not been happening,” Harris told CNN’s Jake Tapper.

Former Vice President Joe Biden has largely sidestepped the issue, but at least one candidate has called it a bad idea.

Sen. Cory Booker, a Stanford graduate, has also been raising campaign cash in Silicon Valley. Also, when he was mayor of Newark, Facebook founder Mark Zuckerberg donated $100 million to improve the city’s schools.

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“I don’t think a president should be running around pointing at companies and saying ‘break them up’ without any kind of process here,” Booker said during an interview.

Big tech had been the darlings of Democratic hopefuls. When he was a candidate, Barack Obama was way ahead of the curve in harnessing their power to fundraising and getting votes. But security breaches and fake election year postings aimed at influencing voters have drawn anger.

Now, some Democratic candidates are leading the populist attacks.

“The fact that Jeff Bezos wanted our taxpayers to pay for his helicopter landing pad just shows how disingenuous he was from the beginning,” said New York Sen. Kirsten Gillibrand about the Amazon founder who eventually pulled plans to locate a second headquarters in the Empire State.

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Sen. Bernie Sanders has agreed with Warren about a total breakup of the tech Big Three. He also likes to go after Amazon for the wages it pays warehouse workers and because it pays no federal taxes.

“Anybody here happen to know how much Amazon paid in taxes last year?” Sanders asked a crowd at a recent rally. “Zero.”

President Trumps has also attacked Amazon’s Bezos, primarily with scathing tweets aimed at his ownership of the Washington Post and its coverage of his presidency.

But Trump has at times sounded like his Democratic rivals on the issue of regulating big tech companies. The Justice Department probe is looking into Amazon, Facebook, Google and Apple to see if they’ve gotten so big competitors don’t stand a chance.