A CBS News Poll released Sunday shows that Democratic presidential contenders Sen. Bernie Sanders and former Vice President Joe Biden are in a first-place tie among Iowa caucusgoers, with both candidates at 25% support. Indiana Mayor Pete Buttigieg is at 21%, while Massachusetts Sen. Elizabeth Warren stands at 16%.

Nationally, Sanders and Biden are both at the top, with an NBC/Wall Street Journal poll on Friday showing the two candidates at 27% and 26%, respectively. Warren is in third place, at 15%, with former New York Mayor Michael Bloomberg listed at 9%. Buttigieg comes in at fifth place, with 7% support.

The Iowa caucus will take place on Monday night, while the New Hampshire primary will take place on Feb. 11. The Nevada Caucus will take place on Feb. 22, while the South Carolina Primary is set for Feb. 29.

Despite having a heart attack in October, Sanders seems to be surging in the race. The Biden campaign believes if Sanders manages to win Iowa, New Hampshire and Nevada, he won’t be able to win South Carolina, where Biden has an advantage.

A new poll from the South Carolina-based Post and Courier-Change Research, however, shows that Sanders is catching up to Biden in the state. The survey shows Biden with 25% support in South Carolina to Sanders’ 20%, a 5% difference. Biden once led in South Carolina polls by as much as 31%.