These Women's March rallies are massive. That's trouble for Donald Trump and the GOP.

Impact

Hundreds of thousands of people gathered in major cities across the country — and the world — on Saturday in a latent protest against President Donald Trump, a massive show of opposition to Trump that could spell trouble for him and his party.

By way of comparison, the enormous rallies on Saturday are far larger than the demonstrations that the Tea Party held in September 2009 in opposition to then-President Barack Obama. At the Tea Party's inception, an estimated 75,000 marched in Washington to protest government spending. Those rallies were some of the first signs of political trouble for Democrats, who a year later were decimated at the ballot box in the 2010 midterms, losing 63 House seats and control of the chamber.

But the fact that these gigantic anti-Trump protests are taking place on Trump's first full day as president — far sooner than the Tea Party galvanized anti-Obama protesters — is even more troublesome for Republican prospects for the 2018 midterm elections.

The immense opposition to Trump at the outset of his presidency is a warning for Republicans on their quest to implement Trump's agenda, including building a wall at the U.S.-Mexico border and cutting Affordable Care Act provisions. 

Protesters at the marches pointedly called out those proposals, including potential GOP cuts to reproductive health care such as birth control and Planned Parenthood funding.

It would also be dangerous for Republicans to brush off the protests with claims that the major cities they were held in were never bastions of Trump support.

Large protests took place in states Trump won, including Iowa, Ohio and Michigan.

Many of the protesters in Washington came from far and wide, some of whom told reporters they had never protested before — meaning a swath of new activists appear to be mobilizing against Trump and his agenda.

Conservatives also made the plea for Trump to not dismiss the rallies.

"Obama was unwise to dismiss the Tea Party," conservative commentator Amanda Carpenter tweeted. "Trump would be unwise to dismiss this. Mock it and it will grow."