CBS News battleground poll shows Biden leading Democrats

For the first CBS News battleground tracker poll, CBS News and YouGov spoke to more than 16,000 registered voters in 18 states that will hold the first primaries and caucuses. Primary voters in those states, from Iowa in early February to the Super Tuesday states in March, will help narrow down the 24 declared Democratic candidates. CBS News elections and surveys director Anthony Salvanto joins "CBS This Morning" to discuss what he found.