Clinton to announce Sunday, with Iowa on horizon

The source added that Iowa will likely be the first stop of Clinton's post-announcement tour. 
The Democratic front-runner has long been expected to make her presidential campaign official this month, and speculation was further stoked when she recently leased office space in Brooklyn, N.Y., for her headquarters. 
That move started a countdown clock with the Federal Election Commission; campaign finance laws dictate that a candidate have 15 days to officially declare a campaign after making such a concrete step. 
In 2008, Clinton's loss in Iowa to then-Sen. Barack Obama was the first crack in her wall of invincibility. By likely kicking off her campaign with an appearance in Iowa, Clinton will hope to improve her fortunes for the 2016 Iowa caucuses. 
Democratic strategists told The Hill earlier this month that Iowa would be a smart place to begin her campaign to show the state that she's willing to work to earn support from Iowans. 
News of the impending announcement trickled out Thursday night. 
The New York Daily News and CNN both are reporting that Clinton will release a video on Sunday at noon announcing her second bid for the White House. 
Business Insider had reported earlier on Thursday that the former secretary of State would announce her long-expected White House bid on either Saturday or Sunday.
Clinton has been hiring aides and quietly staffing up, and an announcement soon would fit with her anticipated timeline. 
The 2016 race already has two official entrants on the GOP side, with Sen. Ted Cruz (R-Texas) announcing late last month and Sen. Rand Paul (R-Ky.) launching his run on Tuesday. 
A Sunday announcement from Clinton could step on the toes of another likely White House hopeful; Sen. Marco Rubio (R-Fla.) is expected to launch his own presidential campaign on Monday evening in Miami. 
This story was posted Thursday at 8:10 p.m. and updated at 9:52 a.m. Friday.