Trump Fumes as Mail Ballots Favor Oz Rival McCormick in Tight Primary

Donald Trump continues to lash out over the GOP Senate primary in Pennsylvania as mail-in ballots favor David McCormick, who is the rival of the former president's endorsed candidate, Dr. Mehmet Oz.

The high-profile primary has tested Trump's influence within the Republican Party, with his endorsement of Oz, who is known for his self-titled television show, raising the ire of many conservatives. The results remain close, and the race will likely head to a recount.

Oz still appeared to hold a narrow lead, leading former hedge fund manager McCormick by just more than 1,000 votes Sunday morning. However, McCormick won more mail-in ballots, leaving the results of the swing state's primary unknown nearly one week after counting began.