Hillary Rodham Clinton is expected to announce her long-awaited second run for president of United States in an online video on Sunday, AP reported. 

Clinton, a former first lady and New York state senator, initially ran for president in 2008, but lost the Democratic nomination to Barack Obama. She then served as Secretary of State during his first presidential term. 

Her new campaign will focus on economic issues, namely boosting security for the middle class and widening opportunities for working families, two of Clinton's senior advisors said Saturday. 

At the same time, the former secretary of state, will also be cast as a "tenacious fighter" who can get results, and in particular, be able to work with Congress, businesses and world leaders.

Following the video announcement on Sunday, those close to her campaign say, Clinton will travel to travel to Iowa, and other states that hold early primaries, for small events with residents. 

Throwing his support behind Clinton on Saturday was her onetime opponent President Obama.

Calling her a "formidable candidate" in their 2008 bid for the Democratic nomination and an "outstanding secretary of state" during his first term in office, Obama stressed she would make an "excellent president."

When asked if he would be part of her campaign, Obama noted Clinton had been "a great supporter of mine in the general election," but added, "I'm not on the ballot so I'm not going to step on her lines."

Not sharing the love for the Clinton was the Republican National Committee, which automatically linked the former secretary of state to Obama and his "failed policies."

"All Hillary Clinton is offering is a continuation of the same big government ideas that have grown Washington instead of the middle class," RNC spokesman Michael Short said in an official statement. "That's why voters want fresh leadership and a new direction, not four more years of Obama's failed policies."

Although Clinton enters the race as an overwhelming favorite for the Democratic nomination - and polling better than any Republican hopeful - her team stressed that the strategy is to avoid taking that nomination for granted.