With contests in two states completed, the most recent NBC News|SurveyMonkey poll found that 56 percent of Republican voters now believe that Donald Trump will be the eventual nominee. That was up from 42 percent a week ago.
This week's tracking poll found Marco Rubio dropping 3 percentage points and John Kasich rising 4 points to a two-month high of 7 percent support.
In the New Hampshire primary, which took place during the period the poll was being conducted, Kasich finished in second place behind Donald Trump, Ted Cruz came in third, and Rubio finished in fifth.
Although Trump maintains his lead nationally with 38 percent support, he will face a different test among a more evangelical and conservative electorate in South Carolina on Feb. 20.
The NBC News|SurveyMonkey Weekly Election Tracking poll is conducted online among 13,139 adults, including 11,417 who say they are registered voters. The results have an error estimate of plus or minus 1.1 percentage points.