Washington(CNN) Bernie Sanders is locked into a tight race with Hillary Clinton nationwide in the fight for the Democratic nomination, according to a Fox News poll released Thursday.
Sanders now leads Clinton 47%-44%, according to the poll. But Sanders' edge is within the survey's margin of error of 4.5 percentage points. The poll sampled 429 registered voters from February 15-17.
Another Fox News poll released Thursday found Clinton holding onto a strong lead in South Carolina, which holds its Democratic primary in a little more than a week. Clinton is leading Sanders, 56%-28% there, according to the poll of 642 likely Democratic primary voters, which carries a margin of error of +/- 4 percentage points.
The South Carolina poll found Clinton winning all subgroups of voters, including men, women, white and black voters.
Other national polls have found Clinton still holding a comfortable lead, however. A new NBC News/Wall Street Journal poll found Clinton leading Sanders 53%-42%, and a CBS News survey found Clinton leading Sanders 47%-39%.
The margins have varied widely, but they all show Sanders closing the gap nationally with Clinton since December, when it appeared she was retaking a firm command of the Democratic field.
The tightening nationwide comes after a CNN/ORC poll found Sanders and Clinton effectively tied in Nevada, just a few days before the Democratic caucuses there.
RELATED: Poll: Clinton, Sanders in a dead heat for Nevada
However, Clinton has held onto a strong lead in South Carolina. CNN's average of South Carolina's Democratic polls found Clinton leading Sanders 56%-32%.