A handful of senior officials are understood to be quietly urging the PM to consider watering down or scrapping the manifesto pledge altogether to see off the growing threat from Reform UK.
After winning five seats at last summer's general election, Reform are seeking to win hundreds of council seats at next month's local elections in England.
The Great Yarmouth MP demanded that Mr Farage, Reform chairman Zia Yusuf and Lee Anderson, the party's chief whip, retract 'false allegations' against him.
In a major speech in Durham, the Reform leader insisted Labour had just as much to fear from his insurgent party as the Tories in its traditional working-class heartlands.
Support for Nigel Farage's Reform has surged in traditional Labour strongholds across the North and Midlands - from 18 per cent at the general election to 30 per cent.
Upset by 'unfounded' reports his party is fielding candidates with 'unsavoury pasts' in the local elections, Reform UK's chief vetting officer Norman Bates, has vowed to 'tighten up' procedures.