– Syrian troops pushed into a rebel-held town near the Lebanese border on Sunday, fighting house-to-house and bombing from the air as President Bashar Assad tried to strengthen his grip on a strategic strip of land running from the capital to the ­Mediterranean coast.

With the regime scoring gains on the battlefield, the United States and Russia could face an even more difficult task in trying to persuade Assad and his opponents to attend talks on ending Syria's 26-month-old conflict. No date has been set, but Washington and Moscow hope to start talks with an international conference as early as next month.

Government forces launched the offensive on the town of Qusair just hours after Assad said in a newspaper interview that he'll stay in his job until elections — effectively rejecting an opposition demand that any talks on a political transition lead to his ouster.

Even though the regime and the main opposition group have not yet committed to attending the conference, U.N. Secretary General Ban Ki-moon said Sunday he is hopeful it can take place "very soon," possibly in early June. In addition to the United States and Russia, he said he has spoken with Britain, France, China and other key parties.

Previous diplomatic initiatives have failed, in part because of divisions within the international community. Russia and the United States have backed opposite sides in Syria.

Still, neither government forces nor rebel fighters have been able to create significant momentum since the uprising against Assad erupted in March 2011 and last year escalated into a full-fledged civil war.

The rebels control large rural areas in the north and east of the country, while Assad has successfully defended his hold on the capital, Damascus, the coastal area and parts of Aleppo, Syria's largest city.

Before Sunday's offensive, Qusair had been ringed by regime troops and fighters from the Lebanese militia Hezbollah, an Assad ally, for several weeks.

Qusair lies along a land corridor between Damascus and the Mediterranean coast, the heartland of Assad's Alawite sect, an offshoot of Shiite Islam. Many rebel fighters are Sunni Muslims and Qusair, overwhelmingly Sunni, had served as a conduit for shipments of weapons and supplies smuggled from Lebanon to the rebels.

The Britain-based Syrian Observatory for Human Rights, an activist group, said 52 people were killed in Qusair, 48 fighters, three women and a male ­civilian.

The Los Angeles Times contributed to this report.