Former Secretary of State Hillary Clinton. REUTERS/Mark Kauzlarich Former Secretary of State Hillary Clinton posted a huge lead in a new Iowa poll released Tuesday.

The Monmouth University survey gave Clinton an eye-popping 65% support among likely Democratic caucus-goers in the state.

Sen. Bernie Sanders (I-Vermont), Clinton's chief primary rival, got just 24%, followed by former Maryland Gov. Martin O'Malley's (D) 5% and Harvard professor Larry Lessig's 1%.

The good-polling news followed Clinton's strong performance in the first Democratic debate, as well as during last Thursday's 11-hour hearing on Benghazi, which the cable-news networks carried live.

Many political observers considered those two events a success for Clinton, whose campaign limped through a difficult summer filled with scrutiny over the private email server she used at the State Department.

However, there is some reason to be skeptical over Clinton's supposed 41-point lead over Sanders in Iowa. On Twitter, The New York Times' Nate Cohn pointed to Monmouth's likely-voter screen: those "who voted in at least one of the last two state primary elections."

That would naturally exclude first-time voters, second-time voters, and others drawn to the higher-interest presidential race next year. Sanders is courting young voters in particular and likely counts on some in these groups to help him win.