Nearly one in four Americans believe that political violence may be justified to "save" the country, a national opinion poll has found.

The 14th annual American Values Survey, carried out by the non-profit Public Religion Research Institute (PRRI) in partnership with the Brookings Institution thinktank, offers a snapshot of America's deepening polarisation and willingness to contemplate taking up arms.

Even as Joe Biden has sought to lower the temperature, support for political violence has increased over the past two years, the survey shows. Today about 23% of Americans agree that "because things have gotten so far off track, true American patriots may have to resort to violence in order to save our country" – up from 15% in 2021.

The PRRI has asked this question in eight separate surveys since March 2021 but this is the first time that support for political violence has risen above 20% in the general population.

One in three Republicans believe that "true American patriots" may have to resort to violence to save the country, compared with 22% of independents and 13% of Democrats – all representing increases since 2021. Almost one in three white evangelical Protestants believe that patriots may have to resort to political violence to save the country, markedly higher than any other religious group.

Support for political violence jumps to even higher levels among Americans who believe that the 2020 election was stolen from Donald Trump (46%); Americans who hold a favourable view of Trump (41%); Americans who believe in the so-called "replacement theory" (41%); Americans who affirm the core tenet of white Christian nationalism, that God intended America to be a new promised land for European Christians (39%).