Hillary Clinton might be a 2-to-1 favorite to win Tuesday's presidential election, according to FiveThirtyEight.com, but she is not in "a terribly safe position," as she is "just one state away" from losing to Donald Trump, pollster Nate Silver said Sunday.

"The electoral map is actually less solid for Clinton than it was for [President Barack] Obama four years ago," Silver, statistician and editor-in-chief, told ABC's "This Week" with George Stephanopoulos. "Four years ago, we had Obama ahead in states totaling 320-some electoral votes.

"Clinton has about 270, so she is about one state away from potentially losing the electoral college."

Some people are saying Clinton's up 5-6 nationally. That's just not a good representation of what the data says. But, she has a lead. — Nate Silver (@NateSilver538) November 6, 2016

Silver's website shows Clinton with a three-point national lead over Trump.

"You'd rather be in her shoes than Donald Trump's, but it's not a terribly safe position," Silver told ABC host Stephanapolous.

Silver pointed to polling that shows "Clinton's a lot weaker in the Midwest" than Obama was in 2012, referencing Trump's 7-point lead in Iowa.

"So, the demographics for Clinton don't work as well when you underperform for white non-college voters," he continued.

"Her electoral college voting in the swing states is a little bit weaker than Obama's."

Silver told ABC a larger number of undecided voters leaves the election "vulnerable, if the undecideds break in a certain way."

"In that sense, both candidates still need a good turnout on Election Day, and still have their work cut out for them," Silver added.

Silver also defended FiveThirtyEight's numbers, which "are much more bullish" for Trump and "more cautious on Hillary," according Stephanapolous.

"We think we have a good process," Silver contended. "Look, you have some forecasts that show Clinton with a 98- or 99-percent chance of winning. That doesn't pass a common sense test. We've seen lots of elections where there is about a 3-percent polling error.

". . . [If] it goes the other way, and all of a sudden, Trump could very easily win electoral college.

"It's all based on history. If you think a 3-point lead is going to be safe 98 or 99 percent of the time, then you probably didn't design the model in a good way."

Silver had gone on a 14-tweet tirade against a Huffington Post editor Saturday night, as Politico chronicled.

He concluded, in defense of his polling methodology: