WASHINGTON - Missouri Sen. Claire McCaskill got a more than three-year head start on the 2016 election, lending her support today to an effort to draw Hillary Clinton into the next presidential race.

McCaskill signed on with the group Ready for Hillary, a super PAC that has emerged as a kind of campaign-in-waiting for the former secretary of state and potential Democratic presidential contender.

"It's important that we start early, building a grassroots army from the ground up, and effectively using the tools of the Internet - all things that President Obama did so successfully - so that if Hillary does decide to run, we'll be ready to help her win," she said in a statement.

Her announcement makes her the first current member of Congress to endorse the draft-Hillary effort, which has been accumulating an impressive list of backers, including Democratic strategist James Carville, long-time Clinton confidant Harold Ickes and former California Rep. Ellen Tauscher.

McCaskill's early support of the group - and by extension, Clinton - also serves to put some distance between the Missouri senator and her decision to endorse Barack Obama during the 2008 presidential primary.

"I worked my heart out to elect him president," she acknowledged in a statement posted on the Ready for Hillary website. "Now as I look at 2016 and think about who is best to lead this country forward, I'm proud to announce that I am Ready for Hillary."

When she endorsed Obama in January 2008, McCaskill called Clinton a "smart woman and a strong leader," but she said she decided to get behind her Democratic opponent "at the fierce urging of my 18-year-old daughter."

Even before that, relations between McCaskill and the Clintons were strained after she said during an appearance on NBC's "Meet the Press" in 2006 that she thought Bill Clinton had been "a great leader, but I don't want my daughter near him."

Seven years later, however, her support for Clinton is unmistakable.

"There is nobody better equipped to be our next President than Hillary Clinton," she said in her statement today.

The announcement also signaled a new chapter for the super PAC, which continues to build its team and brand. In late May, Ready for Hillary announced the formation of a National Finance Council and the addition of former White House political director Craig Smith, who served under Bill Clinton, as a senior adviser.