(CNN) – An early endorsement this week for a 2016 presidential run by former Secretary of State Hillary Clinton merited a phone call from the potential candidate, according to Sen. Claire McCaskill.
Clinton made the call after the senator's Tuesday announcement that she was endorsing a political action committee pushing a presidential run.
"She did call me after this all happened the other day," the Missouri Democrat said on MSNBC's "Morning Joe." "We had a great conversation. I'm not going to talk about what we said. But I think she's got a big decision to make and I think she's in the process of making it."
McCaskill called the endorsement of Clinton an easy decision. "She is by far the strongest, most capable, most qualified candidate for President of the United States," she said. "I am part of a lot of group of people, big huge group of people, that really wants her to run. And it seemed like coming out publicly and stating the obvious, that we all want her to run, was an important thing to do right now."
Despite being an early supporter of then-Senator Barack Obama's 2008 campaign for president, McCaskill has become a strong supporter of Clinton's, expressing a desire to help Clinton get elected when she stepped down as secretary of state in February.
McCaskill became one of the first members of Congress to throw her support behind another Clinton presidential run on Tuesday in a statement put out by the Ready for Hillary PAC.
McCaskill was joined in her support by Sen. Kirsten Gillibrand of New York, who replaced Clinton in the Senate in 2009 when Clinton stepped down to become US secretary of state. Gillibrand, a Democrat, said later Tuesday that “I am personally urging Secretary Clinton to run,” adding that “I’ve told her I plan to support her in any way I can.”
Asked about a potential role in fundraising for the super PAC Thursday, McCaskill said that was not a focus for her or Ready for Hillary. "I'm not excited about spending a lot of my time just trying to get big donors. And I don't think that's what this effort is about," she said. "They're doing an awful lot of social media. They're trying to build a strong database of volunteers." McCaskill described Ready for Hillary as currently more focused on a ground-up effort.
CNN's Paul Steinhauser contributed to this report.