I found this article in my grandmothers 1967 “The World Book”….titled “The GOP Rocks the Great Society in 1966”.

“While the Republicans failed to capture control of Congress, their party was re-established as an effective opposition….In the House, the Democrats won 248 seats and the Republicans 187, previously 295 to 140 respectively….In the Senate, the Democrats won 17 seats and the Republicans 18, reducing the Democratic 67-to-33 majority to 64 to 36.”