Former Secretary of State Hillary Clinton hasn't announced a run for the White House, but Sen. Claire McCaskill endorsed her for president Tuesday. The Missouri senator is just one of many Democratic activists who are pushing Clinton to run in 2016. McCaskill made the announcement on a super PAC website, "Ready for Hillary," which hopes to build a support for a potential Clinton campaign. Clinton is not affiliated with the group. “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,” McCaskill said.