This week, 33 U.S. Senate seats were up for election. Republicans won only 9 of them. This is the smallest number of seats that either major party has won in any election year since 1964, when the Republicans won only 7 seats.

The contrast between the two houses of Congress is extreme. Republicans won 27% of the U.S. Senate seats that were up, but 46% or 47% of the U.S. House seats that were up. There are still 8 U.S. House seats undetermined: Connecticut 2, Florida 13, Georgia 12, New Mexico 1, North Carolina 8, Ohio 2, Ohio 15, and Washington 8. UPDATE: thanks for the comment, which is correct; Texas 23 is also undecided since it has a run-off upcoming.