The Mystery Of Rick Santorum's 'Big' Friday Announcement, Solved

ABC News' Michael Falcone and Shushannah Walshe report:

On Monday, Rick Santorum teased on Twitter: "I have a big announcement coming on Friday! Stay tuned!"

On Tuesday, sources close to Santorum tell ABC News that the former presidential candidate will be announcing the formation of a 501 c(4) organization that he will use to pursue a set of issues he has fought for during much of his political career.

This first wave of issues is likely to focus on an agenda that includes anti-abortion and faith and family causes.

Though Mitt Romney is now at the helm of the Republican Party as its presumptive presidential nominee, Santorum can still remain relevant as a de facto leader of social conservatives.

It's not clear yet where the new 501 c(4) will be operating out of, but last month the pro-Santorum super PAC, the Red, White, and Blue Fund, became a hybrid political action committee that will also work as a traditional leadership PAC to push Santorum's message, support his political travel, cover administrative costs and donate money to candidates he supports with similar views. This new issues-oriented push from Santorum could easily operate out of this leadership PAC.

The announcement could come during Santorum's morning speech at the Conservative Political Action Conference in Chicago. Friday will be a busy day for the former Pennsylvania senator. He is also headlining a fundraiser in Dallas for the Tea Party candidate in the Texas Senate race, Ted Cruz.

But it hasn't been all work and no play for Santorum. Last night he and his old presidential campaign staff met for a reunion of sorts - a trip to a Northern Virginia bowling alley.