By Alex Stevenson
Rebel MPs may defeat the government in the new year as opposition grows to Labour's plans for Heathrow and Royal Mail.
Left-wing pressure group Compass is supporting a campaign against business secretary Peter Mandelson's plans to part-privatise the postal services provider.
Lord Mandelson has Dutch postal firm TNT as a potential candidate for a minority stake in the Royal Mail but rebel MPs are set to table an early day motion rejecting the move.
"Instead of selling off this national asset we'd like to see the service invested in and modernised to ensure it is responsive to people's needs in the 21st century and remains a universal service that is publicly owned," a statement on Compass' website said.
According to the Sunday Telegraph rebel leaders say up to 100 Labour MPs are against the government's plans.
Meanwhile the Guardian newspaper says party resignations are possible if ministers do not back down over proposals to build a third runway at Heathrow.
A decision is due next month after the Cabinet split in December and rebels are planning to individually target ministers to win them over, it reports.
Environmentalists argue the construction of a third runway would undermine Britain's efforts to cut its carbon emissions by 80 per cent by 2050.
Business and transport figures disagree, saying it is much-needed to maintain the airport's position as a transport hub.
The Guardian quoted one backbencher as describing the issue as a "generational battle" between Lord Mandelson and climate change secretary Ed Miliband.
The Commons returns from its new year break on January 12th.