WASHINGTON — President Donald Trump vowed to deliver on a major tax cut for middle-class Americans on Tuesday as the White House and congressional leaders prepared to release details on a tax overhaul proposal that would slash the corporate rate and simplify the nation's tax code.Trump met with Republicans and Democrats from the tax-writing House Ways and Means Committee at the White House, telling reporters he would be releasing a "very comprehensive, very detailed report" on Wednesday that would offer the framework for his top legislative agenda."We will cut taxes tremendously for the middle-class. Not just a little bit but tremendously," Trump said. He predicted jobs "will be coming back in because we have a non-competitive tax structure right now and we're going to go super competitive."The president and congressional leaders were putting the final touches on plans for the first major overhaul to the tax system in three decades, a major Trump campaign pledge that the White House hopes will give Trump a sorely needed legislative achievement.The plan would likely cut the tax rate for the wealthiest Americans, now at 39.6 percent, to 35 percent, said people familiar with the plan.