Presumptive GOP nominee Donald Trump continued his attacks Wednesday against Sen. Elizabeth Warren (D-MA), tweeting that she didn’t “have the guts” to run for the presidency.

He also questioned her Native American heritage again:

Goofy Elizabeth Warren didn’t have the guts to run for POTUS. Her phony Native American heritage stops that and VP cold. — Donald J. Trump (@realDonaldTrump) May 11, 2016

Trump’s comment comes after Warren, in an interview with Mic News, refused to rule out being Democratic frontrunner Hillary Clinton’s running mate.

Here’s how Warren responded:

We get it, @realDonaldTrump: When a woman stands up to you, you’re going to call her a basket case. Hormonal. Ugly. — Elizabeth Warren (@elizabethforma) May 11, 2016

Trump and Warren have engaged in an Twitter flame war for days. Both have used the social media platform to criticize and attack one another, typically with multiple tweets at a time. Most recently, after Trump went on a rant against Warren last week, the Massachusetts senator hit back and called his attacks “weak.”

The feud continued throughout the day. Here’s a sampling:

If the people of Massachusetts found out what an ineffective Senator goofy Elizabeth Warren has been, she would lose! — Donald J. Trump (@realDonaldTrump) May 11, 2016

Goofy Elizabeth Warren is now using the woman’s card like her friend crooked Hillary. See her dumb tweet “when a woman stands up to you…” — Donald J. Trump (@realDonaldTrump) May 11, 2016

Our Native American Senator, goofy Elizabeth Warren, couldn’t care less about the American worker…does nothing to help! — Donald J. Trump (@realDonaldTrump) May 11, 2016

Goofy Elizabeth Warren lied when she says I want to abolish the Federal Minimum Wage. See media—asking for increase! — Donald J. Trump (@realDonaldTrump) May 11, 2016

Isn’t it funny when a failed Senator like goofy Elizabeth Warren can spend a whole day tweeting about Trump & gets nothing done in Senate? — Donald J. Trump (@realDonaldTrump) May 11, 2016

If it were up to goofy Elizabeth Warren, we’d have no jobs in America—she doesn’t have a clue. — Donald J. Trump (@realDonaldTrump) May 11, 2016

Do you think you’re going to shut us up, @realDonaldTrump? Think again. It’s time to answer for your dangerous ideas. — Elizabeth Warren (@elizabethforma) May 11, 2016

You care so much about struggling American workers, @realDonaldTrump, that you want to abolish the federal minimum wage? — Elizabeth Warren (@elizabethforma) May 11, 2016

You feel so much for people with college debt, @realDonaldTrump, that you raked in millions scamming students with Trump University? — Elizabeth Warren (@elizabethforma) May 11, 2016

You’re so concerned about Wall Street, @realDonaldTrump, that you say you’d “absolutely” repeal Dodd-Frank? — Elizabeth Warren (@elizabethforma) May 11, 2016

When asked what gov should stop doing, @realDonaldTrump said overseeing banks! How can you be tough on Wall Street by letting them off? — Elizabeth Warren (@elizabethforma) May 11, 2016