The story

In the final hours before the Iowa caucuses, candidates are trying to gain the support of the undecided and make sure their supporters show up.

Three Democrats and two Republicans are virtually tied at the top, according to the latest CNN/Opinion Research Corp. poll, and last-minute decisions from undecided voters could push a candidate to the head of the pack.

This week's poll shows that 17 percent of likely Democratic caucus-goers said they are still trying to decide which candidate to support, and more than a quarter of Republican caucus-goers said they are still trying to decide.

The White House hopefuls are taking different crunch-time approaches as they try to woo Iowans one day before they head out to vote.

Former North Carolina Sen. John Edwards, who has been on a 36-hour tour through Iowa, attended a rally around midnight and made stops throughout the morning Wednesday. Read full article »

CNN's Jessica Yellin and Dana Bash contributed to this report.

All About Hillary Clinton • Barack Obama • Mike Huckabee • Mitt Romney • Iowa