The Fox News poll (conducted jointly by Anderson Robbins Research (D) and released yesterday has Donald Trump with 35% leading second place candidate Texas
The anti-establishment candidates (Trump, Cruz, Carson, Carly Fiorina and Kentucky Senator Rand Paul) total 70%. This is the level the anti-establishment candidates have polled at for several months, with the only change being supporters shuffling among the anti-Establishment candidates. It is difficult to see a scenario in which an Establishment candidate like Rubio or New Jersey Governor Chris Christie can win in this environment.
The previous Fox News poll in mid-December had Trump at 39% and Cruz second at 18%. No news there. The changes are well within the margin of error.
The major change in the Fox Poll is the general election head-to-head matchups. In the mid-December Fox poll, Trump trailed Clinton by 11%. The new poll has him leading her by 3%. That is a gain of 14% in less than a month.
Trump is not the only Republican whose fortunes against the likely Democratic nominee have greatly improved. In the earlier Fox poll, Cruz polled even with Hillary Clinton. In the most recent one he leads by 7%. Rubio went from a 2% lead in the mid-December Fox poll to 9% in the most recent one.
To summarize, in about three weeks, Trump gained 14% in head-to-head polling with Hillary Clinton, while Cruz and Rubio each gained 7% during that time.
It should be noted that a Fox poll in mid-November showed Republicans doing much better in head-to-head matchups than mid-December Fox poll. But that was also during a time Hillary Clinton was experiencing substantial set-backs during her campaign. She's widely considered to have corrected those problems although Vermont Senator Bernie Sanders continues to garner substantial Democratic support in the polls. In fact, the Fox poll shows Sanders with 39% support, the highest he's ever polled nationally.