VIENNA (Reuters) - Austrian Chancellor Christian Kern said on Tuesday he was losing patience with his conservative coalition partners, raising the prospect of a government collapse that could play into the hands of the far-right Freedom Party.

Kern, a Social Democrat, gave interviews in which he called on the conservative People’s Party to back at least some of his recent proposals on economic and political reforms or face a breakdown of their coalition, which runs until 2018.

Spats within the centrist bloc are common and neither party appears to have a vested interest in an early parliamentary election, since polls suggest the anti-immigrant Freedom Party (FPO) would win. But Kern’s remarks were unusually aggressive.

“Our patience is being seriously tested,” Kern told the tabloid Kronen Zeitung.

“We have to provide results, otherwise there is no need for this government,” he told newspaper Der Standard, which said he had called on the People’s Party (OVP) to agree to unspecified “concrete measures” by Friday.

Whether Kern’s comments were bravado or a serious threat remains to be seen. Polls regularly show the FPO in first place with support of roughly a third, followed by Kern’s Social Democrats on around 27 percent and the OVP on about 19 percent.

The FPO candidate also put in a record performance in last year’s presidential election, coming within a percentage point of becoming the first freely elected far-right head of state in Europe since World War Two.

The FPO has been gaining support for years, helped by fears about economic insecurity and immigration in a country that was caught in Europe’s migration crisis in 2015. Frustration has also grown at the two centrist parties that have dominated Austrian politics for decades and which many now see as ineffective.

Kern, who took over as head of the government in May, gave a slickly produced 105-minute speech this month unveiling a long list of proposals on issues ranging from cutting unemployment to achieving equality for women and reforming education.

The speech was partly an attempt to win back voters who have drifted towards the FPO, but some also saw in his list of proposals dubbed “Plan A” an implied threat to his coalition partners - Plan B being the end of the coalition.

Whatever his intention, the mood within the coalition appears to have soured since. In an apparent reference to the speech, conservative Vice Chancellor Reinhold Mitterlehner told the daily Die Presse that “Kern puts appearances before work”.

The two sides are due to hold a meeting on Wednesday to hammer out a set of coalition priorities.