Elizabeth Warren appears at Clinton campaign headquarters

NEW YORK, June 18 (UPI) -- Massachusetts Sen. Elizabeth Warren paid a visit Friday night to the Brooklyn-based headquarters for Hillary Clinton's presidential campaign.

Warren, who has been floated as a potential vice presidential nominee, posed for photos with rank-and-file staff and made brief remarks, calling Clinton "one tough cookie" and urging the staff, "Don't screw this up."

Clinton was not at her headquarters during Warren's visit.

Warren was in New York on a fundraising swing. The liberal senator has earned praise from Democrats as a particularly effective attack dog for Donald Trump. Warren earned Trump's ire on several occasions for tweets disparaging him.

In a speech recently, Warren referred to Trump as a "thin-skinned racist bully" and Trump responded, tagging Warren with the moniker "goofy Elizabeth Warren."

Warren is not the only potential vice presidential candidate to make a stop at Clinton's campaign headquarters. Also seen there recently, according to CNN, were two Obama cabinet secretaries, Julian Castro and Tom Perez.