Congress on alert for new attack next month

US Capitol police and members of Congress are on high alert for attacks fuelled by the QAnon conspiracy theory that Donald Trump should be inaugurated as the ‘‘real’’ president next week.

Followers of the online cultlike movement have alighted upon March 4 as the date for Trump’s triumphant return, based on a combination of beliefs. Authorities fear that this may lead some to descend on Washington, DC again after last month’s riot at the Capitol.

Tensions increased this week amid warnings from the acting Capitol police chief that a bomb attack could be planned for President Joe Biden’s first state of the union address to both chambers of Congress.

QAnon grew rapidly from obscure online postings in 2017 into a movement followed by millions, based around the myth that Trump would save America from a cabal of Satan-worshipping paedophile Democrats.

The anonymous Q persona has not posted since December 8, and the movement has fractured since the failure of its core prophecy – that Trump would win in a landslide and arrest the liberal establishment in an event known as the Storm. It has left many adherents casting around for clues about what happens next.

Immediately after January 6, a number of Q followers latched on to March 4, the date when presidents used to be inaugurated. The passing of the 20th amendment to the US Constitution in 1933 shifted it to January 20.

This became conflated with theories from the so-called sovereign citizen movement that the US ceased to be an independent nation in 1871, when the District of Columbia was incorporated while Ulysses Grant was the 18th president. This has inspired the theory that Trump will become the 19th ‘‘true’’ president on March 4.

Senior figures in Congress have sounded alarm bells. Democrat Adam Smith, chairman of the House armed services committee, said last week: ‘‘Some of these people ... are thinking, ‘Maybe we should gather again and storm the Capitol on March 4’.’’