A top aide to Hillary Clinton, the presumed Democratic frontrunner in the 2016 White House race, is visiting the key primary states of New Hampshire and Iowa this week, stirring rumors that the former secretary of State is inching close to officially announcing her presidential bid, the Associated Press reported.

Robby Mook, whom the AP dubbed Clinton's "campaign manager-in-waiting," was in New Hampshire on Monday and Tuesday and is headed to Iowa on Wednesday and Thursday for meetings with party officials and activists, unidentified Democrats familiar with his plans told the news service.

The first-in-the-nation caucuses are traditionally held in Iowa, while New Hampshire has long been the first state to kick off the primary calendar. Clinton has signaled that she intends to compete vigorously in both races, along with those in other leadoff presidential states, such as South Carolina and Nevada.

In New Hampshire, Mook stayed at the homes of Clinton supporters and was being joined by Mike Vlacich, expected to be Clinton's state director, Bloomberg detailed.

Mook, who managed New Hampshire Sen. Jeanne Shaheen's 2008 campaign, "has many longtime friends in the state," the business publication added; that includes Democratic Party Chairman Ray Buckley, who is also meeting with Clinton's advisers.

In Iowa, he will be traveling with Matt Paul, slated to lead Clinton's campaign in the Hawkeye State; the two are set to meet with Democrats in Des Moines, Cedar Rapids and Iowa City.

Tyler Olson, a former Iowa Democratic Party chairman, told the AP that the motives behind the visit was fairly obvious.

"There's no reason for them to come except for the fact that they are interested in Iowa," Olson noted. "They're going to be interested in Iowa, and they're going to make a big commitment."

Jim Demers, who chaired Barack Obama's 2008 campaign in New Hampshire, compared the efforts of the former secretary of State to those of her one-time challenger.

"It's not dissimilar to what the Obama team did," he said.

Demers, who this time around supports Clinton, added that he was looking forward to hearing from the former New York senator's advisers.