BALTIMORE (Reuters) - The U.S.-led battle against Islamic State militants controlling parts of Iraq and Syria is gaining steam and will show more progress by year’s end, Vice President Joe Biden said on Thursday. Biden touted the recent success of U.S. efforts backing Iraqi troops against the Islamic State in Iraq as part of a broad defense of Obama administration foreign policy. “I promise you, after Ramadi, watch what happens now in Raqqa in Syria and what happens in Mosul (Iraq), by end of this year,” he told U.S. House of Representatives Democrats, in Baltimore for a three-day retreat. Iraqi forces, boosted by U.S. training, have evicted insurgents from large parts of Ramadi, leading to speculation that they could have success elsewhere against the Islamic State. “We’ve taken back collectively 40 percent of the territory  they occupy,” Biden said. White House spokesman Josh Earnest, asked about Biden’s remarks, said he had not yet heard them. But he added, “Obviously, we’re going to need to get ISIL  leaders out of Mosul and out of Raqqa and that’s a significant task. We know that they’ve been dug into those cities for a while now, and that means it’s going to be hard to dig them out.” ISIL is one of the acronyms referring to Islamic State. The Democratic vice president attributed recent successes to more engagement by European countries and Turkey. “The president has finally got the attention of Europeans to pony up because they haven’t been doing much of anything,” Biden said, adding, “I spend too much time probably with President Erdogan, but Erdogan has seen the Lord. Things are changing because of self-interest.” Biden and Turkish President Tayyip Erdogan discussed ways to deepen cooperation in the fight against Islamic State in a meeting in Istanbul on Saturday, according to a White House statement on Sunday. 