The independent surveys show the senator from Vermont continues to close the gap with the former secretary of state while voters’ familiarity with Sanders and his favorability ratings are steadily rising, Sanders’ pollster said. Moreover, Sanders’ agenda has dominated the debate. His message about a rigged economy propped up by a corrupt campaign finance system “is driving the issue agenda within the Democratic primary,” Tulchin wrote.

Looking ahead to next year’s general election, Sanders is much more popular than Clinton with independents and he is much better positioned with Republicans, factors Tulchin said raise “real questions as to which of these leading Democratic candidates is in fact the best positioned for the general election.”

In several recent surveys Sanders outperformed Clinton in matchups with Republicans. In a Wall Street Journal/NBC News poll released on Nov. 3, Sanders outpolled Donald Trump by nine points, 50 percent to 41 percent, and the Vermont senator beat Sen. Marco Rubio of Florida by five points, 46 percent to 41 percent. In a McClatchy/Marist poll released Nov. 13, Sanders outpolled Donald Trump, former Florida Gov. Jeb Bush, Sen. Ted Cruz and Carly Fiorina. Sanders outperformed Clinton against Cruz and Bush. In a new poll in Colorado, Sanders fared better than Clinton when pitted against four leading Republican White House hopefuls. Tim Malloy, assistant director of the Quinnipiac University poll, said Clinton “would get bruised and beaten by all the top GOP opponents, and absolutely crushed” by Rubio or Carson.

With the first primaries and caucuses less than three months away, the survey findings warn that Clinton “has real vulnerabilities within the Democratic primary electorate,” particularly for “being too close to special interests and Wall Street.”

The analysis of recent polls for CBS News, NBC News, The New York Times and The Wall Street Journal underscored the fact that Sanders has closed the gap with Clinton since he declared his candidacy on April 30. Half a year ago, Sanders barely registered in polls and pundits dismissed his chances. Today, Sanders “has made tremendous progress and is now the leading Democratic challenger to Hillary Clinton and within striking distance of her,” according to the memo.

Nationally, Sanders trailed by 30 points in a New York Times/CBS News poll in September (58 percent to 28 percent) but trailed by only 19 points (52 percent to 33 percent) in the latest survey. In fact, Sanders gained a net 5 points on Hillary over the past month, a period one published report declared “the best month ever” for Clinton.

In Iowa and New Hampshire, the states with the first caucuses and primary elections next February, the survey show that the more people know about Sanders the better they like him. “The bottom line is that as Democratic primary voters in key early voting states become more familiar with Sanders, they very much like what they hear and are much more likely to vote for him, thereby putting Sanders on a trajectory to make the Democratic primary horserace even more competitive as he campaigns aggressively and begins to advertise to get his message out more broadly.,” the pollster wrote.

To put the numbers in historical context, then-Sen. Barack Obama in 2007 trailed Clinton by 27 points at the same stage of that campaign. A Gallup Poll released on Nov. 16, 2007, put her ahead with 48 percent of the vote to Obama’s 21 percent.