Presidential announcement mania is coming. Look fast or you'll miss it.

Five more candidates — four Republicans and one Democrat — are expected to formally announce their presidential intentions between now and June 4.

Already, six Republicans and two Democrats have announced and found any momentum was fleeting.

The upcoming batch of Republican announcements includes: Rick Santorum, the former U.S. senator from Pennsylvania and 2012 Iowa caucus winner, on Wednesday; former New York Gov. George Pataki on Thursday; Sen. Lindsey Graham of South Carolina on June 1; former Texas Gov. Rick Perry on June 4.

Former Maryland Gov. Martin O'Malley is expected to announce on Saturday his bid for the Democratic nomination.

McClatchy Washington Bureau