By now, Mitt Romney’s “binders full of women” have been opened, parsed and closed.

But what happened in the hours after the former Massachusetts governor inadvertently spawned an online sensation in describing his efforts to hire women for his Cabinet may forever be seared in the minds of Web-savvy political strategists.

Mining such memes, a skill honed by the quirky communities on Reddit and Tumblr, has become an essential tool for messaging and fundraising as political action committees, outside interest groups and party committees on both sides of the aisle compete to harness the power of a trending phrase.

Just minutes after the Republican presidential candidate uttered the phrase during Tuesday’s debate, the liberal super PAC American Bridge 21st Century scooped up four domain names built around variations of the phrase. By 3 a.m. Wednesday, BindersFullofWomen.com — a website featuring briefs on Romney’s record on women’s issues — was fully operational. The next day, the PAC, which has raised $10.7 million so far this cycle, used the site as the basis for a fundraising appeal.

“Donate $10 or more right now and American Bridge will deliver a binder full of FACTS about women to Mitt Romney’s campaign headquarters,” Kathleen Kennedy Townsend, the group’s chairwoman and a former lieutenant governor of Maryland, wrote in an email to supporters. A spokesman declined to discuss how much money the effort had raised.

In the meantime, PACs run by the AFL-CIO and EMILY’s List pushed the meme on their Facebook pages, racking up hundreds of “likes.” The union also targeted advertisements on Twitter to users who mentioned debate moderator Candy Crowley. Twitter handles, such as @RomneyBinders, and Tumblr themes built around the phrase attracted tens of thousands of followers. Other liberal groups such as Americans United for Change prepared fundraising pleas, citing Romney’s awkwardly phrased remark.

It was the most rewound and re-watched moment of the debate, according to TiVo Research and Analytics Inc. Still, the major takeaway is that it all happened in an instant.

“It has a short shelf life, which is why my reaction was to get something up quickly and be a place that people could go to ridicule the comment,” said Matt Ortega, a Democratic digital media strategist whose website — MittsBindersFullofWomen.com — was live by the end of the debate. “I was able to get it up quickly because I am not beholden to anyone’s approval.”

While presidential and Congressional campaigns may not be as nimble as outside groups, party committees have tried to advance memes of their own by advertising on hash tags and creating destination websites such as RomneyTaxPlan.com. The website, unveiled by the Democratic National Committee before Tuesday’s debate, is designed to look like a project of the official Romney campaign, but when visitors try to click a button labeled “Get the Details,” it dances across the screen ahead of the cursor.

The Republican National Committee tried to capture a similar audience with ObamaIsntWorking.com, but for the most part, conservatives have not reacted as aggressively.

Indeed, liberal groups seem to have an edge. And none quite like MoveOn.org. More than 3 million people viewed 35 Facebook posts from the liberal PAC throughout the night, according to a spokesman for the group. One of its most successful posts — a spoof of the signature line from the movie “Dirty Dancing” featuring a picture of Patrick Swayze overlaid with the words “No One Puts Baby in a Binder” — received 21,645 “likes” and 5,143 “shares.”

“It’s a big strategic investment by the AFL-CIO,” said Jeff Hauser, a spokesman for the union. “You’re going to see more and more of this thing, better and faster.” But, he added, “we were really fast on binders and Big Bird.”