As Republican delegates gather in Cleveland, Donald Trump spent Sunday morning taunting Clinton to choose liberal darling Elizabeth Warren as her running mate.

“I hope that Crooked Hillary picks Goofy Elizabeth Warren, sometimes referred to as Pocahontas, as her V.P. Then we can litigate her fraud!” he tweeted to his 9.8 million followers.

“If Goofy Elizabeth Warren, a very weak Senator, didn’t lie about her heritage (being Native American) she would be nothing today. Pick her H,” Trump continued.

The attack comes after Warren, a Democratic senator from Massachusetts, went on a Twitter tirade following Trump’s announcement that he chose Indiana Governor Mike Pence as his running mate.

“.@realDonaldTrump & @mike_pence are a perfect match: Two small, insecure, weak men who use hate & fear to divide our country & our people,” Warren wrote Saturday.

Warren, who has been an outspoken critic of Trump’s candidacy, also called out the business magnate and the Indiana Tea Partier for their stances on women’s reproductive rights.

“Of COURSE @realDonaldTrump – a guy who calls women fat pigs & bimbos – picked a VP who is famous for trying to control women’s bodies,” Warren tweeted.