ATHENS (Reuters) - Former Greek premier Alexis Tsipras's Syriza party is narrowly ahead of its main conservative rival, the New Democracy party, but its lead is shrinking, according to two opinion polls published on Saturday.
Syriza is on course to win 26.5 percent of votes in a snap election on Sept. 20, slightly ahead of New Democracy on 25.9 percent, a poll by Kapa Research showed. But its lead shrunk to 0.6 percentage points from 3.1 in a previous poll by the same pollster in late August, as New Democracy closed the gap.
A separate poll by Marc showed Syriza on 24.4 percent, and New Democracy on 24 percent.
Tsipras had called the election to win a fresh mandate for a tough bailout program agreed with the country's creditors. But having started out as the frontrunner, Syriza's lead has crumbled in recent days, making the election unexpectedly close.
Two other polls published last week showed New Democracy beating Syriza for the first time.
About a third of the respondents in Saturday's Marc poll would prefer a national unity coalition government taking over after the election, but Tsipras has so far ruled out doing any such deal with New Democracy.
Tsipras had been a popular leader as he defied the creditors over imposing austerity measures, but he later capitulated to their demands as the economy came close to collapse.
His popularity has fallen sharply since, and some recent polls show him to be less popular than the head of New Democracy Evangelos Meimarakis.
For the two polls published on Saturday, undecided voters made up 11.6 percent to 14.1 percent of the vote respectively.
(Reporting by Angeliki Koutantou; editing by Matthias Williams)