Fox News released a poll on impeachment Sunday, the results of which differ from three recent major polls, all of which show more registered voters oppose impeachment than support it.

Those three polls from Quinnipiac University, Monmouth University, and NPR/PBS NewsHour/Marist University all show registered voters oppose impeachment of President Trump and his removal from office by margins ranging from three percent to seven percent. But the Fox News Polls shows registered voters support impeachment and removal from office by four percent.

A Quinnipiac Poll released last Tuesday showed registered voters oppose impeachment and removal from office by a 51 percent to 45 percent margin.

A Monmouth University Poll released last Wednesday showed registered voters oppose impeachment and removal from office by a 51 percent to 44 percent margin.

An NPR/PBS NewsHour/Marist Poll released on Monday showed registered voters oppose impeachment and removal from office by a 49 percent to 46 percent margin.

In contrast, the Fox News Poll released on Sunday showed registered voters support impeachment and removal from office by a 50 percent to 46 percent margin.

Though the Fox News Poll results actually show a decline in support for impeachment among respondents when compared to the results from of its poll conducted between October 6 and October 8 of this year, when 51 percent of poll respondents favored impeachment and removal while 43 percent opposed it, the current seven to 11 point differential compared to the three other major recent polls is difficult to explain.

The answer may lie in the methodology used by the Fox News Poll, which was a random sample of 1,000 registered voters and was conducted “under the joint direction of Beacon Research (D) and Shaw and Company Research (R) . . . by Braun Research, Inc. of Princeton, NJ” voters between December 8 and 11 and has a margin of error of three percent, according to the statement released along with the poll.

That statement, however, provided little information on the methodology and demographics of the respondents, other than party self- identification, which was 46 percent Democrats, 41 percent as Republicans, and 12 percent independents. While the differential between Democrats and Republicans among the other three polls varied from +6 Democrat (Quinnipiac) to +4 Democrat (Monmouth), which was similar to the Fox News Poll differential of +5 Democrat, the respondent samples in two of the other three polls included significantly more independents.

Respondents to the Quinnipiac Poll were 34 percent Democrat, 28 percent Republican, and 37 percent Independent/Other.

Respondents to the Monmouth University Poll were 30 percent Democrat, 26 percent Republican, and 43 percent Independent/Other.

Comparable data for the NPR/PBS NewsHour/MaristPoll was not immediately available.

Data for breakdown by age group, income, and race were available in the initial statement that accompanied the Fox News Poll.

One clue may be found in the relatively high percentage of respondents who were contacted by cell phone (77.9 percent) versus landline phone (22.1 percent):

Landline (221) and cellphone (779) telephone numbers were randomly selected for inclusion in the survey using a probability proportionate to size method, which means phone numbers for each state are proportional to the number of voters in each state.

Landline usage is higher among older voters. Cellphone usage is higher among younger voters.

Respondents to the Fox News Poll were remarkably left-leaning on a number of issues:

68 percent support Sen. Elizabeth Warren’s proposal of a wealth tax of two percent on an individual’s worth above $50 million in addition to income tax , while only 26 percent oppose it

63 percent support legalizing the recreational use of marijuana on a national level

53 percent support making minor changes to Obamacare while largely leaving the law in place, while 38 percent want to get rid of it

52 percent oppose building a wall along the US-Mexico border, while 44 percent support it

Among the other surprising results from the Fox News Poll were these two unusual results regarding the fairness of the impeachment inquiry:

45 percent of respondents think Congressional Democrats are running the impeachment inquiry fairly, while 42 percent think it is not being run fairly.

52 percent of respondents think the Trump administration is not being cooperative enough with the impeachment inquiry, while 36 percent think it is being cooperative enough

Fox News Poll respondents have been consistently left-leaning for some time.

For instance, in the poll conducted between September 11 and September 14, 2016–less than two months before Donald Trump was elected president–55 percent of respondents opposed building a wall along the US-Mexico border, while only 41 percent supported it. Despite those poll results, Trump, who made building the border wall a main promise of his campaign, easily won the presidency in the electoral college vote, 306 to 232 (faithless electors changed the final vote to 304 to 227), even though he lost the popular vote by two points.

Lacking more robust information from Fox News on the poll’s methodology and demographics, it remains difficult to explain why its results vary so much from those of the Quinnipiac Poll, the Monmouth University Poll, and the NPR/PBS NewsHour/Marist Poll.