British Prime Minister Boris Johnson faces his first rebellion on Tuesday over his decision to allow China's Huawei a role in building the country's 5G phone network.
In January, Britain decided to allow Huawei into what it said were non-sensitive parts of the network, with its involvement capped at 35%.
The decision angered the United States, which wants to exclude the Chinese company from the West's next-generation communications systems because of security concerns. It has urged Britain to rethink.
A group of Johnson's Conservatives, said to number between 30 and 50 lawmakers, oppose the decision. They are planning to back a change, or amendment, to the Telecommunications Infrastructure Bill, despite that legislation having very little to do with the security of the network.
They want the companies termed by British security experts as "high-risk vendors", which includes Huawei, stripped out of networks completely by the end of 2022.
"We hope to curb the government's enthusiasm for installing hardware produced by a company that they acknowledge to be 'high risk'," David Jones, a Conservative lawmaker who signed the amendment, told Reuters.
The Conservative rebels acknowledge they do not as yet have the numbers to force a change to government policy. But they hope if more than 20 lawmakers vote against a newly-installed government it might be a sizeable warning shot across the bows to influence Johnson to take a harder line.