That is patently untrue. See also here and here.
They were forecast to lose seats when they won both Houses of Congress in 1994.
Umm.. no. No they weren't. This is what was forecast in 1994 for the House.
Alan Abramowitz: GOP net gain of 27
Charlie Cook: GOP net gain of 37
Ronald Lester: GOP net gain of 28
Frank Luntz: GOP net gain of 38
Mary Matalin: GOP net gain of 43 (to win control)
Chris Matthews: GOP net gain of 36
Ralph Reed: GOP net gain of 31
Bill Schneider: GOP net gain of 32
Marty Tolchin: GOP net gain of 38
Ron Walters: GOP net gain of 32
Fred Wertheimer: GOP net gain of 34
Mark Shields: GOP net gain of 35
Al Hunt: GOP net gain of 36
Bob Novak: GOP net gain of 44 (to win control)
Margaret Carlson: GOP net gain of 30
Doug Bailey: GOP net gain of 36
Fred Barnes: GOP net gain of 38
Morton Kondracke: GOP net gain of 48 (to win control)
John McLaughlin: GOP net gain of 42 (to win control)
Jack Germond: GOP net gain of 28
Eleanor Clift: GOP net gain of 30
So, pundits universally forecast the GOP to gain seats, and a lot of them for that matter.
Of the above, the following also predicted that the GOP would pick up the Senate: Alan Abramowitz, Charlie Cook, Frank Luntz, Mary Matalin, Chris Matthews, Ralph Reed, Ron Walters, Mark Shields, Al Hunt, Bob Novak, Margaret Carlson, Doug Bailey, Fred Barnes, Morton Kondracke, and John McLaughlin.
The following predicted a 50/50 Senate: Bill Schneider, Marty Tolchin, Fred Wertheimer, and Jack Germond.
Only Ronald Lester predicted that the Dems would hold the Senate, but he still predicted that the GOP would pick up five seats.
It's very unseemly when you just make things up like that........
So, I guess it was taking the House that was not predicted.
I think Sink thinks that before the 1994 election, the Dems were ahead in the generic vote, not that pundits predicted that the GOP would lose seats. I doubt if Sink is right, but that was his point. One needs to dig up generic polls in 1994. I myself was shocked that the GOP won 53 seats in 1994, although I was not following things as closely back them, because there was no internet for me back then. All I remember was Charlie Cook's prediction, which I saw on the tube. The thrust was the GOP would win about 30-40 seats, not 53. And at this time of the year in 1994, it was probably more like 20 seats.