Boris Johnson is facing the prospect of his first House of Commons defeat since the December general election, as a former Tory leader urges a rebellion against the Government over the inclusion of Huawei into the UK's 5G network.
Sir Iain Duncan Smith has tabled an amendment to the Telecoms Infrastructure (Leasehold Property) Bill - which is currently being debated - aiming to ban "high-risk vendors" like the Chinese tech giant from the network after 2022.
The move is backed by several high profile Tories, including former cabinet ministers Damian Green and David Davis, the chair of the Commons Foreign Affairs Committee Tom Tugendhat and the chairman of the Tory backbench 1922 Committee Sir Graham Brady.
Despite support for the amendment, there is not much hope that the Government - which has a Commons majority of 80 - could be defeated.
Some 26 Tory MPs have signed the amendment, but it will take at least 41 votes against the government for the rebels to win.
Ahead of the debate, the culture secretary wrote to the rebels to dissuade them from voting against the government.
Oliver Dowden told the MPs this is “not the right bill” to rebel on and reiterated how Huawei won’t have full access to 5G.
He added: "Over time our intention is to reduce reliance on high risk vendors as market diversification takes place.
"We want to get to a position where we do not have to use a high risk vendor in our telecoms networks at all."
He says the government will do this by working with partners "to develop new supply chain capacity in our critical national infrastructure.
The Commons debate follows Prime Minister Johnson's decision to allow Huawei help build 5G, which was apparently met with fury by Donald Trump.
The US President reportedly blasted Mr Johnson with “apoplectic” rage during a heated phone call regarding the 5G move.
The US claims allowing Huawei into 5G would compromise the UK's security, due to the tech firm's links to the Chinese state.
But a former chairman of BT warned excluding Huawei from Britain's 5G network will "significantly set back" the Government's ambitions to extend broadband access.
Sir Mike Rake, who now acts as an adviser to the Chinese tech giant, hit out at what he said were "ill-informed assertions" about the dangers of allowing the company access to the UK's critical national infrastructure.
Tory backbencher Bob Seely, one of the MPs behind the move, said they were "laying down a marker" ahead of other legislation later in the year to establish a comprehensive telecoms security regime.
He said there was "growing momentum" within the party with "three or four MPs" expressing concern to the whips for every one likely to vote for the amendment next week.
"We want to work with the Government, not to defeat it.
"We want to co-operate with the Government to get a better solution," Mr Seely said.
Huawei vice president, Victor Zhang, said: "Over the last 18 months, the Government and two parliamentary committees have conducted detailed assessments of the facts and concluded there is no reason to ban Huawei from supplying 5G equipment on cyber security grounds.
"We have been operating in Britain for nearly 20 years, and played a vital role in the development and delivery of 3G and 4G for people across the UK.
"Cyber security requires high and common standards across the telecoms industry, which Huawei has always supported. Creating a 5G Britain rightly requires scrutiny and we will work with the Select Committee to address their questions in the coming months."
Mr Johnson's official spokesman told a Westminster briefing: "Market failure has left us in this position and we want to get to a position where we do not have to use a high risk vendor in our telecoms network.
"We will keep the 35% market cap under review.
"Our intention is for this share to reduce as market diversification takes place.
"We will work with the US and our partners to diversify the telecoms market and develop alternative suppliers."