 Correspondent Jeremy House. An updated political forecast gives the GOP a 65% chance of holding its majority in the House, while winning control of the upper house of Congress. Decision Desk HQ says Republicans have increased their advantage by one point since its forecast earlier this week, and are now seeing its favorites to clinch 11 of 16 up for Graves House seats. The forecast also gives Donald Trump a 58% chance of capturing the White House, and Republicans an 82% chance of flipping the Senate.