By Susan Heavey
WASHINGTON (Reuters) - Former U.S. Secretary of State Hillary Clinton has not committed to a run for president in 2016 but on Tuesday she picked up an endorsement from Missouri Senator Claire McCaskill, who announced she is supporting a group encouraging Clinton to run for the White House again.
McCaskill, who in 2008 backed Barack Obama over Clinton in the Democratic primaries, became the first member of Congress to announce her support for Clinton.
She praised the political action committee called Ready for Hillary For using the Internet to build support in the hope that Clinton will again seek the job her husband, Bill, held from 1993 to 2001.
"If Hillary does decide to run, we'll be ready to help her win," McCaskill said in a statement supporting Ready for Hillary.
Clinton, 65, has been coy about her plans since leaving the Obama administration in February. Recent polls have indicated she is far and away the most popular potential Democratic candidate for 2016, and that most Americans would prefer her to several potential Republican contenders.
The prospect of a Clinton candidacy has hung over recent efforts by congressional Republicans to cast the deadly attack on a U.S. mission in Benghazi, Libya, last September as a failure of the Obama administration - and Clinton's State Department in particular - to provide adequate security at U.S. outposts abroad.
Last week Clinton started her official Twitter account, describing herself as, among other things, a "wife, mom, lawyer, women & kids advocate." She alluded to her future as "TBD" - to be determined.
Last week she also made her first major speech since stepping down as secretary of state, outlining an effort to work on children's and women's issues.
During the speech to her husband's charitable group, Clinton echoed themes of education and economic empowerment that could be the focus of a potential campaign.
"We understand you can't look to government to solve all our problems, we can't trust the market to solve all our problems. We need those partnerships," she told the Clinton Global Initiative conference.
"Certainly, I will be focused on applying lessons learned from around the world," she said.
McCaskill's endorsement highlights the bond-building that continues between the Clinton and Obama camps.
Obama won the Democratic Party's nomination in 2008 partly because of a campaign that emphasized grassroots organization and organizing and fundraising over the Internet. Clinton initially was seen as the candidate to beat in the 2008 primaries but her campaign suffered from infighting and organization problems.
Clinton went on to work for Obama, her former colleague when she represented New York in the Senate, as secretary of state.
McCaskill praised Ready for Hillary for courting Obama supporters, saying such efforts were critical.
"They're helping to show that regardless of who you supported for president back then, we can all agree today that there is nobody better equipped to be our next president than Hillary Clinton," she said.
With Obama's job approval ratings now below 50 percent in several recent polls, analysts say that if Clinton decides to run, she would need an agenda that is distinct from his.
During her speech last week, she praised some of Obama's priorities, such as expanded preschool, but hinted at her own priorities.
"In too many places in our own country, community institutions are crumbling, social and public health indicators are cratering, and jobs are coming apart," she said.
(Editing by David Lindsey and Bill Trott)