Speaking with ABC's George Stephanopoulos on Friday, Biden acknowledged that Sanders is ahead in some polls, refusing to guarantee victory.
"I think it's going to be really close, George. It's neck and neck. Bernie's up, I'm up. Actually, there's basically a statistical tie."Biden acknowledged that the way caucuses are structured could hurt his chances in Iowa, given that he is supported by older voters, while Sanders' supporters skew younger.
"You know, George, this situation better than anybody. If there's a big snowstorm in certain parts of the country -- certain parts of the state, it could have an effect," he said.
"So the caucus is -- you have to be able to come to a gymnasium, stay there for two, three hours, and it takes a lot of commitment," the former vice president added.
Biden also said that he feels "good" about his chances in other states, adding that the response to his campaign has been "great" across different parts of the country. He finished the interview by vowing to endorse whoever ends up winning the Democratic nomination.
"Yes, I'm going to -- whomever wins the nomination, I'm going to endorse," Biden said.
A glance at the RealClearPolitics average of polling data reveals that Biden's lead in Iowa has gradually melted away over the past couple of months.
Massachusetts Sen. Elizabeth Warren and former South Bend, Indiana Mayor Pete Buttigieg both spent a few months topping the polls in the Hawkeye State. Biden has, meanwhile, recovered, but Sanders' lead has been growing steadily, and he is now the front-runner in the first-in-the-nation caucus.
According to the polling average, Sanders enjoys the support of 23.8 percent of Iowans. Biden is polling at 20.2 percent, Buttigieg is at 15.8, and Warren appears dangerously close to being non-viable with 14.6 percent of the vote. The rest of the field is polling in single digits.The polling in Iowa reflects a broader trend, suggesting that Biden and Sanders have separated themselves from the rest of the pack. The primary race is once again starting to look like a two-way contest, so the former vice president and the Vermont senator have spent the past few weeks contrasting records and attacking each other.
Sanders and members of his campaign have criticized Biden over his past support for cutting Social Security, and Biden has hit back at Sanders by pointing out that the Vermont senator is not a member of the Democratic Party, but a lifelong Independent.