Former Secretary of State Condoleezza Rice. (Charles Dharapak/AP)

Minus the mystique of Sarah Palin, the Republican National Convention lost about 17 million viewers Tuesday.

About 20 million people tuned in to the 10 p.m. hour on the second night of the GOP party confab.

Four years ago, a whopping 37 million tune in at the same time, when then GOP VP nominee Sarah Palin addressed the nation for the first time.

Leading the exodus: CNN viewers.

Four year ago, CNN logged 6.1 million viewers when Palin spoke. This year 1.3 million tuned in to hear Ryan speak — a 78 percent plunge.

MSNBC’s story isn’t much prettier — down 56 percent, convention to convention, on Night 2, securing an average of 1.4 million viewers, versus 3.3 mil in ’08 in the timeslot.

Faring far better, Fox News Channel, which clocked 9 million viewers the hour Sarah Palin spoke, averaged 7.7 million viewers on Tuesday at 10 – a drop of just 15 percent.

FNC was the runaway ratings leader this past Tuesday, in primetime and in this key 10 p.m. FNC and widened its lead over its competitors compared to the first night of the convention.

But the broadcast networks were also missing Palin, though maybe not as much as CNN.

ABC, for instance, lost 52 percent of its audience Tuesday night compared to RNC Night 2 in ’08, averaging just 2.9 million viewers compared to 5.9 million.

Still, ABC pulled in more viewers Tuesday than CBS, which logged 2.6 million. Four years ago, CBS snagged 4.6 million viewers curious to see Palin.

NBC finished first among broadcasters, though it trailed FNC by about 3.6 million viewers, which, coincidentally is about how much NBC trailed its own performance on Night 2 of the RNC in ’08.

Once again, the broadcasters covered the confab in that hour only (each network’s coverage ran a few minutes past 11).

The cable-news networks, however, devoted their prime time to convention coverage. FNC averaged 5.9 million viewers, beating the combined audience of MSNBC (1.3 million) and CNN (1.1 million). (Ratings for some networks that covered the convention, including PBS, were not available at press time.)