A Donald Trump Donald John TrumpObama calls on Senate not to fill Ginsburg's vacancy until after election Planned Parenthood: 'The fate of our rights' depends on Ginsburg replacement Progressive group to spend M in ad campaign on Supreme Court vacancy MORE rally that was scheduled for Friday night in Chicago was indefinitely postponed over security concerns after hundreds gathered outside the UIC pavilion to protest the GOP front-runner's event.

A Trump rally earlier Friday in St. Louis, Mo., resulted in dozens of arrests amid reported scuffles between protesters and Trump supporters.