PARIS (Reuters) - The small center-left PRG (Radical Party of the Left) has threatened to quit France's Socialist-led government unless a 2015 budget includes more concessions to a pressured middle class, putting at risk a fragile parliamentary majority.
The PRG is the last of the junior coalition allies in the government of Prime Minister Manuel Valls after the exit of the Greens in April, highlighting the government's increasing fragility and the unpopularity of President Francois Hollande.
Were its three ministers to quit the cabinet, the PRG could add to rebel voices on the Left in parliament and thwart the safe passage of key legislation including next year's budget.
The PRG, which said its voice is being ignored by the government, said it wants a more equitable progressive tax burden to protect the middle class.
A concession to low earners included in the draft 2015 budget to cancel the existing lowest income tax band will put additional fiscal pressure on the middle class, the PRG says.
The party also opposes possible measures to save money on France's generous family allowances.
"We aren't looking for a clash. We don't want to leave the majority," Radical Left party leader Jean-Michel Baylet told Soir3 television on Sunday.
"But unless there are advances, we consider that the current circumstances don't allow us to remain members of this government."
Baylet said the party would meet with Valls on Monday and a decision would be made whether to stay or go before a party meeting on Friday.
Valls' government narrowly survived a confidence vote last month in the assembly, where it holds a single-figure majority, but the possible loss of the PRG as allies could increase the clout of rebel parliamentarians already insisting on less belt-tightening for families and low-earners.
The PRG has threatened to quit the government before, most recently in August over a territorial reform that aims to halve the number of regions in France's administrative map. The party enjoys strong support in rural counties, where the reform could threaten its number of regional officials.
The threat of departure of yet another government ally underscores the unpopularity of Hollande, whose approval ratings are at historically low levels.
Anti-austerity concessions made to rebels in the assembly have already watered down public spending cuts the European Union deems crucial in reducing France's public deficit.
Paris has said it will not meet an EU-imposed budget deficit ceiling of 3 percent of gross domestic product in 2015, setting up a showdown with EU authorities.
(Reporting By Alexandria Sage; editing by Mark John)