As we head into the biggest day of the presidential primaries — Super Tuesday — Donald Trump and Hillary Clinton continue to hold commanding leads in their respective primaries, according to our new national numbers from the past week.

In fact, very little has changed, according to our NBC News|SurveyMonkey Weekly Election Tracking Poll for the week of February 22 through February 28, 2016. The poll was conducted online among a national sample of 30,294 adults aged 18 and over.

Among registered Republicans, Trump has hit a new high, and he now commands the support of 40 percent of Republicans. Coming in second is Marco Rubio at 21 percent, and Ted Cruz is third with at 18 percent. Following a debate performance that many thought was his most aggressive, Rubio’s support increased 5 percent in the last week, and his support is higher than it has ever been, but he still trails Trump by nearly two-to-one. Cruz continues to hold fast in third place, although his support slipped a percentage and the Texas senator's support is now the lowest it has ever been.

In the Democratic contest, Clinton holds a 10-point lead over Bernie Sanders among registered voters. Sanders’ level of support is also at an all time high in our poll — 41 percent — but Clinton’s support has remained above 50 percent since the beginning of the year, and she has kept a double-digit lead throughout the month of February.

Sam Petulla contributed graphics to this story.

The NBC News|SurveyMonkey Weekly Election Tracking poll was conducted online from February 22, 2016 through February 28, 2016 among a national sample of 30,294 adults aged 18 and over, including 26,859 who say they are registered to vote. Respondents for this non-probability survey were selected from the nearly three million people who take surveys on the SurveyMonkey platform each day. Results have an error estimate of plus or minus 1.0 percentage points. A full description of our methodology and the poll can be found here.