President Obama is happy to talk campaigns with former Gov. Martin O'Malley, but only if the Maryland Democrat calls in and asks to set something up, White House spokesman Josh Earnest said on Wednesday.

"I certainly wouldn't rule out a future meeting between the president and Governor O'Malley," Earnest said after Obama sat down with Sen. Bernie Sanders at the White House to discuss the Vermont independent's bid for the Democratic presidential nomination.

"I'm not aware of any active discussion…but I wouldn't rule out that if Governor O'Malley makes a request like that, that we wouldn't find a way to find some time on the president's schedule for it," Earnest said.

Obama wants Democrats to have a "robust" primary, which is why he has met with Sanders and former Secretary of State Hillary Clinton, but not endorsed anyone, Earnest said.

Any "presidential attempt to sort of head off that debate at this early stage by weighing in on the primary isn't really going to benefit any of the candidates," Earnest added.

Sanders, who requested the meeting, said he believes Obama is being "even-handed" in his approach so far.

As to the Democratic National Committee squelching an unscheduled debate in New Hampshire, Earnest said that Obama agrees that the debate schedule is up to the DNC.

The DNC, "who actually is neutral in this race, should decide exactly what that debate schedule should be," Earnest said of the president's thinking.