Libertarian presidential nominee Gary Johnson admits that his donations to charity are "almost nonexistent."

"My charitable contributions would be negligible — I mean just, really almost nonexistent," the former New Mexico governor told CNN on Friday, following the announcement by Hillary Clinton's campaign that she and her husband donated close to 10 percent of their adjusted gross income to charity in 2015.

Johnson stressed that his wealth "does not even approach Hillary Clinton."

The Clintons, though, gave all their donations to the Clinton Foundation and a related charity.

When asked what percentage of his income he has given to charity, Johnson said: "For me, giving to charity, I've always viewed that the things that I do in my life contribute to making lives better. That what I've done."

He also estimated that his effective tax rate was around 20 percent last year; the Clintons' was 34 percent.

Johnson also told CNN that he does not expect 2012 Republican presidential nominee Mitt Romney to endorse him "for all sorts of reasons," even though he expressed the "possibility" of it last month.

"I'm not expecting it. So given my expectations, everything's a bonus," he said of Romney, who has blatantly said he will not support the GOP's nominee in Donald Trump.

Johnson continues to remain a long-shot candidate, aiming to just get onto the debates. He needs to have a minimum of 15 percentage points in national polls by September to reach the stage but currently polls around 8 percent.