Boris Johnson faces his Tory rebellion since the general election tonight over Chinese phone giant Huawei.
At least 26 Conservative MPs have signed a shock move calling for the firm - which critics brand a tool of the Chinese state - to be banned from the UK's 5G network from 1 January 2023.
If at least 40 Tory MPs back the amendment in Parliament at 7pm tonight, it could spell Boris Johnson's first House of Commons defeat since his thumping 80-seat election victory in December.
Or the Tory leader might be forced to back down to save face with the rebels - who include former Tory leader Iain Duncan Smith and ex-Cabinet ministers Damian Green and David Davis.
A defeat would scupper the Prime Minister's bid to let "high-risk vendor" Huawei run up to 35% of the UK's super-fast 5G network, which the Tories vowed to build as a key election pledge.
After months of debate ministers gave Huawei - which denies being a tool of the Chinese state - a limited role in building the UK's phone infrastructure back in January.
Scroll down for the full list of Tory rebels
The firm can provide parts for up to 35% of the total network and will not be allowed to control the technology's roll out entirely in any city. The company is also to be excluded from safety-critical networks in critical infrastructure and from the network in sensitive locations.
But Tory MPs warned the decision would be "nesting a dragon" and it infuriated the US - with Donald Trump allegedly flying into an "apoplectic rage" in a phone call with Boris Johnson .
US Secretary of State Mike Pompeo branded China's communist party “the central threat of our times” saying: “It’s not about a technical back door. They have the front door.”
Warning the 5G deal was a "risk", he added: “We will never permit American National Security information to go across a network we do not have trust and confidence in."
The Sun reports today's amendment to the Telecommunications Infrastructure Bill was published despite 11th-hour talks with Downing Street to head off a Tory rebellion.
The MPs' amendment would ban any vendors deemed "high-risk" by the National Cyber Security Centre from being used by the UK's mobile network operator.
One rebel admitted they might not have the 40 MPs needed to defeat the government. They told The Sun: "We might lose this vote, but the momentum is on our side”.
Another rebel, former Army intelligence officer Bob Seely, told the newspaper: "We are talking to the government, because we all want the best outcome for our country."
“But what we must hear from it is a timetable to get high risk tech out of our system so we can protect our people. It’s got to be no way Huawei.”
The PM’s official spokesman said: “We are clear-eyed about the challenge posed by Huawei. Its market share is kept under review."
“We have said we want to reduce the share as market diversification takes place. We need to see how quickly the market is able to diversify.”
Full list of Tory MPs who've signed the amendment so far
Sir Iain Duncan Smith
Bob Seely
Mr Owen Paterson
Tom Tugendhat
Mr David Davis
Damian Green
Damian Collins
Sir Graham Brady
Anne Marie Morris
Sir Christopher Chope
Craig Mackinlay
Mr William Wragg
Julian Knight
David Morris
Jack Lopresti
Anthony Mangnall
Henry Smith
Tim Loughton
Richard Drax
Sir Robert Syms
Mr David Jones
Mrs Sheryll Murray
Dr James Davies
Fiona Bruce
Mr Mark Francois
David Warburton
