Sen. Kamala Harris (D-Calif.) on Sunday took aim at President Trump's proposed wall along the U.S.-Mexico border, describing it as a "medieval vanity project" during remarks at the official launch of her 2020 bid for president.

Harris spent a portion of her speech in Oakland, Calif., describing the meaning behind her campaign slogan, "For the People," a reference to her time as a prosecutor.

"For the people meant fighting transnational gangs that traffic in drugs, and guns and human beings," she said. "And I saw their sophistication, their persistence and their ruthlessness."

"And folks, on the subject of transnational gangs, let's be perfectly clear: The president's medieval vanity project is not going to stop them," she continued, prompting raucous applause from the crowd.

The president's demand for more than $5 billion in funding for a wall along the southern border triggered a partial government shutdown that ended last Friday after 35 days.

While Trump has portrayed the structure as a necessary deterrent to crime and illegal immigration, Democrats have insisted that a wall is "medieval," ineffective and a poor use of taxpayer money.

A group of bipartisan lawmakers are set to negotiate border security funding over the next three weeks. Trump has indicated he may declare a national emergency to build the wall or shut down the government again should the agreement not be to his liking.

Harris announced last week her intention to run for president in 2020, but formally kicked off her campaign with Sunday's rally in California.

Harris joins Sens. Elizabeth Warren (D-Mass.) and Kirsten Gillibrand (D-N.Y.), as well as Rep. Tulsi Gabbard (D-Hawaii), former San Antonio Mayor Julián Castro and South Bend, Ind., Mayor Pete Buttigieg among the Democrats who have officially declared their candidacy.

The field is expected to grow in the coming months, with former Vice President Joe Biden, Sen. Bernie Sanders (I-Vt.), Sen. Cory Booker (D-N.J.) and former New York City Mayor Michael Bloomberg among those expected to announce their plans for 2020.