Just in case your tinfoil hat is getting a bit scuffed and torn in spots, Lindsay Beyerstein has some fresh aluminum for you, with an excerpt from the quoted in James Mann's book The Rise of the Vulcans:
Nixon, Rumsfeld, and Gallup

Benj of For the Record on The Danger of the Gallup:

By now the explanation for the Gallup poll's massive pro-Bush slant is clear -- they overpoll republicans. Why? The Gallup boss is a big GOP donor.

Harmless, you say? -- Maybe not, if Dems get discouraged and don't vote. Jess suggests a more sinister purpose: camouflaging the e-theft of the election.[...]

People forget that Gallup has colluded with the Republicans before. Donald Rumsfeld was caught on the Watergate tapes recounting his covert ops to the President. The Rise of the Vulcans, James Mann describes how Rumsfeld ingratiated himself with Nixon by working his Princeton connection with George Gallup Jr.

Mann writes:

There is no evidence from the Nixon tapes that Rumsfeld tried to sway the outcome of Gallup's polling results. Rumsfeld did, however, manage to gain some advance information about what Gallup's upcoming poll results would show, giving Nixon an edge of a few days to prepare. Rumsfeld appeared to realize that in these contacts he was asking Gallup to go beyond the traditional independent role of the pollster. At a White House session in October, 1971, Rumsfeld urged Nixon to keep these contacts with the Gallup Poll top secret:

RUMSFELD: Say, I just want to report, sir, about my conversation with George Gallup [Jr].

NIXON:Oh, yeah, you went to school with him, didn't you?

RUMSFELD: I did. And I kind of want to be awful careful about telling people around the building that I'm talking to him. Because all he's got in this business is his integrity.--[ROTV, pg 17]

Mann goes to say that Gallup agreed to postpone the release of polling data for almost a month while Nixon was visiting China. The record shows that Rumsfeld and HR Haldeman claimed that Gallup sat on the data in order to help Nixon.