Reasons given for the split are vague. In a statement, Gallup says that both journalism and survey research have been “changing and evolving” over the past two decades – and it also points to the popularity of its own website, Gallup.com, which attracted 18 million unique visitors last year.

“Gallup.com will remain the primary source for Gallup polls conducted in the US and around the world,” the firm said.

USA Today says it is already in the final stages of negotiating a polling deal with a new partner, while Gallup says it will “evolve the polling it conducted in partnership with USA Today in some different and new strategic directions”.

Gallup is already known to be reviewing its methodology in light of its presidential election polls, which hinted at a win for failed Republican challenger Mitt Romney in November.

The focus of the review is on the way Gallup determines which respondents are likely to vote. After the election – and Gallup’s popular vote estimate of 50% Romney, 49% Obama – editor-in-chief Frank Newport wrote in his blog that: “Our final estimate of registered voters was an unallocated 49% for Obama, 46% for Romney. The transition to likely voters moved that to the unallocated 49% Romney, 48% Obama… 

“Our traditional ‘bootstrap’ method of identifying likely voters is self-weighting – letting voters’ responses to questions determine their probability of voting. This bears investigation. We will use the government’s post-election data, along with internal evidence, to see if further assumptions, investigations, or changes might be necessary.”