Germany's main opposition party is celebrating a bittersweet 150th birthday, as polls showing it trailing badly in the race for September elections, with a visit from a recent left-wing winner who has lost his luster — French President Francois Hollande.

The Social Democratic Party is marking Thursday's anniversary with festivities in Leipzig, the eastern city where it was born in 1863. Guests include its main rival: popular conservative Chancellor Angela Merkel, who's just been named the world's most powerful woman by Forbes magazine for the third consecutive year.

The Social Democrats face an uphill struggle to oust Merkel in parliamentary elections Sept. 22. Polls show the party trailing her conservatives by more than 10 points, though they also show no majority for Merkel's current center-right coalition.