Pres. Trump To Rally In Georgia Ahead Of Senate Runoffs

President Trump plans to hold a rally in Georgia to support Republican candidates before the runoff election. He announced his visit via Twitter, and the Republican National Committee is organizing a rally in Dalton, GA, where Senators Kelly Leffler and David Perdue will speak. They are competing against Democratic challengers Raphael Warnock and Jon Ossoff.

What is the significance of the event mentioned in the text?

Who are the Democratic challengers facing the Republican candidates?