Support for Germany's Greens has dropped to its lowest level in almost 15 years, an Emnid poll showed, dimming the chances that a left-leaning coalition could wrest power from Chancellor Angela Merkel in September's election. The weekly survey for Bild am Sonntag newspaper showed the Greens shedding one point to 6 percent - the environmental party's weakest showing in that poll since September 2002. That leaves it hovering just above the 5 percent threshold that parties need to enter the national parliament. The poll echoes results in two other polls last week, one conducted by Forsa for magazine Stern and broadcaster RTL, and another by pollster INSA. Declining support for the Greens could reduce the chances of a left-leaning "red-red-green" alliance of the Social Democrats (SPD), the far-left Linke party and the Greens after a Sept. 24 election. The Emnid poll showed Merkel's conservatives adding one percentage point to 36 percent, expanding their lead over the SPD, which remained unchanged at 31 percent. The Social Democrats are junior partners in the current coalition, but hope to unseat Merkel and lead a new government. The far-left Linke and the anti-immigrant Alternative for Germany remained unchanged at 9 percent. The pro-business Free Democratic Party (FDP), the junior partner in Merkel's 2009-2013 conservative-led government, dropped one percentage point to 5 percent, teetering on the cusp of being able to reenter parliament. It crashed out in 2013 after failing to clear the 5 percent threshold. Also Watch: Emnid polled 1,412 eligible voters from April 13-19, largely before Frauke Petry, co-leader of the AfD, shocked supporters by announcing on Wednesday that she would not lead the party's campaign for the September elections. The AfD, which has lost momentum as migrant arrivals have dropped, looked set to move further to the right after delegates to a party congress on Saturday refused to discuss Petry's motion to shift the party to the "mainstream". Support for the SPD has stagnated following strong gains earlier this year after the party named former European Parliament President Martin Schulz as its candidate to run against Merkel.