An overwhelming majority of Republicans—at 74 percent—believe it’s likely that Donald Trump was wiretapped or otherwise subject to government surveillance while he was running for president, according to a CBS News poll released on Wednesday.

The results suggest that Republican voters have largely accepted the president’s claim—which he first made earlier this month in a tweet—that President Obama ordered a wiretap of Trump Tower. That’s despite the fact that there is no evidence to substantiate his charge, which PolitiFact has labeled “false.” So why do so many Republicans appear to believe the president if there’s no concrete evidence to back him up? A few factors help explain the polling result.

To start, it’s possible that many Republicans either believe Trump or are willing to say they do out of a sense of partisan loyalty. While 74 percent responded that it’s either “very likely” or “somewhat likely” that Trump’s offices were wiretapped or surveilled, the same percentage of Democrats rated those same possibilities “not very likely” or “not at all likely.”

This isn’t the first time survey data has found a partisan split over an unsubstantiated allegation made by the administration. In January, the White House falsely claimed that Trump’s inauguration featured “the largest audience to ever witness” such a ceremony. Yet one survey found that when voters were presented with photographs from Trump’s and Obama’s inaugurations, and asked to say which one had more attendees, Trump supporters were “significantly more likely to answer the questions wrong” than Clinton voters,  according to The Washington Post’s Monkey Cage blog. (Obama’s inauguration drew a larger crowd.)

“While this may appear to be a remarkable feat of self-deception,” as my colleague Julie Beck put it, it may be that people simply wanted to signal support for Trump. “In these charged situations, people often don’t engage with information as information, but as a marker of identity. Information becomes tribal,” Beck explained.

Another reason why Republican voters may be more likely to accept Trump’s allegations is because other partisans, in particular House Intelligence Committee Chairman Devin Nunes, have muddied the waters around the wiretapping claim. Last week, Nunes delivered a bombshell—if difficult to parse—announcement to reporters that the intelligence community had “incidentally collected information about U.S. citizens involved in the Trump transition.”

Still, Nunes’s statement did not vindicate Trump’s claims that his New York City residence had been wiretapped by his predecessor, and the California congressman had previously stated that there was no “physical wiretap of Trump Tower.” FBI Director James Comey has also said that he has “no information” to support Trump’s tweeted claims, and he told Nunes’s committee earlier in the month that neither does the Justice Department.

Nevertheless, Nunes provided the White House with a degree of political cover with his statement on incidental collection last week, and that may have helped still-wavering Republican voters accept Trump’s accusations. In recent weeks, the White House has tried to bolster Trump’s claims by arguing, in effect, that he should be taken seriously, but not necessarily literally. “The president used the word wiretap in quotes to mean, broadly, surveillance and other activities,” White House Press Secretary Sean Spicer said earlier this month. In light of that, Nunes’s claim that transition-team intelligence had been collected may have been enough to either convince some Republican voters that Trump had been vindicated or make them feel comfortable asserting that he had.

The exact wording of the survey question could also have contributed to the results. The CBS poll does not explicitly quote from Trump’s original accusation, and instead asks a question more in line with the White House interpretation of Trump’s claims—that by mentioning a wiretap in his tweet, the president was discussing surveillance more generally. It reads: “How likely do you think it is that Donald Trump’s offices were wiretapped, or under government surveillance, during the 2016 presidential campaign?” The question also does not mention Obama.

Faced with competing and overlapping claims from a variety of sources, Republican voters may opt to privilege the information that doesn’t cast doubt on the president’s trustworthiness. As Beck explained, “doubling down in the face of conflicting evidence is a way of reducing the discomfort of dissonance,” with dissonance defined as “the extreme discomfort of simultaneously holding two thoughts that are in conflict.”

Liberals and conservatives alike are susceptible to believing, or at the very least circulating, incorrect information that appears to confirm their political worldview. So-called “fake news” has found an audience among progressives and liberals, just as it has found an audience in pro-Trump circles, too. There’s little sign that this embrace of false beliefs, especially those seemingly rooted in partisanship, will end anytime soon.