Hillary Clinton will formally announce her candidacy for the 2016 presidential campaign on 12 April while traveling to Iowa, the Guardian reported on 10 April.

According to the Guardian's source, the Democrat will announce her bid on Twitter at 12pm EST on Sunday. The former secretary of state will follow up her social media announcement with a video and email announcement and a series of conference calls regarding her campaign tour.

Nick Merrill, Clinton's spokesman, did not confirm when Clinton would begin her campaign schedule but another source told the Guardian she would kickoff in Iowa.

Clinton, who would be the first Democrat to declare a formal bid in the upcoming election, has dropped several hints about a possible presidential campaign in the last couple of weeks. On 3 April, her team signed a lease for a campaign headquarters in Brooklyn. The lease followed several reports of new hires, including former Obama aides and Ready for Hillary employees.

While Clinton is believed to be the frontrunner among potential Democratic candidates, recent polls reveal she will have to work hard to regain supporters in key swing states. A Quinnipiac University poll released on 9 April showed Clinton has lost her edge against Republican candidates in Colorado and Iowa.

In Iowa, the poll revealed she edges several Republican candidates, except for Arkansas Governor Mike Huckabee and Kentucky Senator Rand Paul. Clinton managed to tie Huckabee at 42%, but fell behind Paul (43% to 42%). Recent reports about her new campaign strategy show Iowans should expect to see a lot more of the former first lady.

Clinton's second run for the White House is expected to be a complete reversal of her first campaign in 2008. A report by CNN earlier this week stated her 2016 campaign will be more personal, with fewer mentions of her own ambitions and more attention to voters' needs.

If elected, the 67-year-old would become the first female president of the United States.