Former US Vice President Al Gore speaks about climate change during the Fourth Annual Rhode Island Energy and Environmental Leaders Day at the US Capitol in Washington, DC, June 11, 2013.

Story highlights

Al Gore said Monday that while he would back the Democratic nominee he was not ready to endorse in the primary

The 2000 Democratic presidential candidate also decried the tone of the 2016 race

CNN  — 

Former Democratic presidential candidate Al Gore declined to endorse either Hillary Clinton or Bernie Sanders, decrying the tone of the 2016 campaign but alluding only to “signals” that he’s received soliciting his support.

Gore spoke with NBC’s “Today” on Monday to mark the tenth anniversary of the release of “An Inconvenient Truth,” the climate change documentary that Gore made central to his political advocacy, after he failing to become president in 2000.

The conversation included the upcoming election, and Gore – who served as vice president to Clinton’s husband – wouldn’t pick a side.

“Has either Democrat sought your endorsement yet?” NBC’s Anne Thompson asked.

“I’ve gotten signals that you can interpret that way,” Gore said, but did not expand on who had reached out to him or his preference this primary, in the clip aired on NBC.

Thompson added at the end of her report that Gore “has been lifelong Democrat” and planned to back the Democratic nominee.

Gore’s withholding of his endorsement comes as many Democratic leaders fret about unifying the party, with the fractious primary contest between Sanders and Clinton extending into the summer while likely GOP nominee Donald Trump works to consolidate Republican support.

The 2000 Democratic presidential nominee also criticized the tone of the 2016 race, saying, “I’m one of millions who sometimes just – I do a double take. ‘Whoa, what was that?’”

“It’s been unusual,” he added.