WASHINGTON — For days, top Republicans in Congress demanded the release of James B. Comey’s memos about President Trump, threatening Rod J. Rosenstein, the deputy attorney general, with a subpoena if he failed to share the highly anticipated documents written by the former F.B.I. director.

But if Mr. Trump and his allies believed that Mr. Rosenstein’s refusal would deliver a pretext to call for his firing, as Democrats asserted, his decision to quickly release all the memos late Thursday night foiled that plan. The memos leaked to reporters hours after being delivered to lawmakers in both parties.

And the seven memos, in which Mr. Comey methodically documented his interactions with the president in real time, did little to help Republicans undermine Mr. Comey’s credibility or expose contradictions with his best-selling, tell-all book. Taken together, the 15 pages of detailed notes largely back up the stories that Mr. Comey told in congressional testimony, in the pages of his memoir, “A Higher Loyalty,” and during numerous television and radio interviews.

“I’m not quite sure how this improved the strategic posture of those who want to dismantle the special counsel investigation,” said Representative Jamie Raskin, Democrat of Maryland. “This is a tactic that has backfired. From what I’ve seen of the Comey memos, they bear out completely the authenticity of his reports and his own credibility.”