Democrats on the House Intelligence Committee are preparing to release 3,000 Russia-linked Facebook ads, according to people familiar with the matter, in what would offer the broadest picture yet of how the social network was manipulated during and after the 2016 U.S. presidential election.

The ads, which Facebook Inc. identified as bought by the pro-Kremlin Internet Research Agency, could be released as early as this week, some of the people said. But the timing could slip to next week or later as Facebook and Democrats haggle...