WASHINGTON – President Donald Trump ramped up his warnings of a suburban “invasion” Wednesday in a tweet that critics described as both sexist and racist.

The president’s missive, in which he suggested a Black senator from New Jersey would be in charge of overseeing an “invasion” of neighborhoods that would undermine the “safety” for “the suburban housewife,” came a day after his rival in the November election made history by choosing a Black woman as his running mate.

In the tweet, he made reference to the policies of Sen. Cory Booker, D-N.J., who is Black. As a presidential candidate last year, Booker released a plan to make housing more affordable and get rid of housing discrimination.

“The ‘suburban housewife’ will be voting for me,” Trump wrote. “They want safety & are thrilled that I ended the long running program where low income housing would invade their neighborhood. Biden would reinstall it, in a bigger form, with Corey Booker in charge!”

The tweet came a day after presumptive Democratic nominee Joe Biden chose Sen. Kamala Harris, D-Calif., as his running mate, marking the first instance that a woman of color will run on a major presidential ticket in the U.S.

Trump has hammered on an Obama-era anti-discrimination housing regulation his administration recently ended as proof of his fealty to “suburban voters,” which critics view as a code for “white voters.” Trump has tweeted that suburbanites would experience lower crime rates and higher property values because he ended the rule.

Trump has characterized the rule as expanding low-income housing but it, in fact, is an attempt to address longstanding racial segregation in U.S. housing policy. The rule is tied to the 1968 federal Fair Housing Act, signed by President Lyndon Johnson.

Jane McManus, director of the Center for Sports Communication at Marist College, tweeted a play on the term “dog whistle:”

“Is there such a thing as a dog scream?” she asked.

Joyce Vance, a former federal prosecutor and University of Alabama law professor, tweeted: “The morning after Joe Biden selects a Black, Asian woman as his VP, the only thing Trump brings is an explicit appeal to racism.”

The Lincoln Project, an anti-Trump group of Republicans and former Republicans, tweeted: “You sad, racist old man.”

Democrats slammed the tweet.

“Trump is racist and sexist and thinks he can use racism to motivate his supporters,” said Josh Schwerin of Priorities USA Action, a political action committee that supports Democratic candidates. “Trump’s racism is one of the big reasons voters, including those in the suburbs he thinks he’s trying to appeal to here, are ready to get rid of him.”

Former Bill Clinton press secretary Joe Lockhart called it “racism in its purist form.”

“It’s what the Trump team thinks will get him re-elected,” tweeted Lockhart, a prominent supporter of Biden. “They’re counting on the silent racist majority. Let’s prove them wrong once and for all.”

Trump supporters said the president is raising a valid election issue: public safety.

“Trump is rightly demanding laws are enforced, property is defended and criminals are arrested,” said Matt Mackowiak, a Republican strategist based in Texas. “It’s a stark contrast with the Dems. Kamala Harris led the effort to bail out violent protesters during the Floyd protests.”

Trump, who polls show is trailing in battleground states, has tried to frame Democrats as seeking to “abolish” the nation’s suburbs, a key constituency for both parties.

Booker aides did not immediately respond to a request for comment.