WASHINGTON — President Barack Obama's sweeping gun-control package faces an uncertain future in Congress, where majority Republicans in the House of Representatives are rejecting his proposals while the president's allies in the Democratic-controlled Senate are stopping well short of pledging immediate action. Obama's $500 million plan marks the most comprehensive effort to tighten gun laws in nearly two decades as he tries to build on the high emotions over last month's school shooting in Connecticut, where a gunman with a legally purchased high-powered rifle left 20 young children and six adults dead. The president's announcement Wednesday appealed to both common sense and conscience, but frustrated observers of Congress say the growing partisan divide is little swayed by either. “To make a real and lasting difference, Congress must act,” Obama said. “And Congress must act soon.” Obama must try to push through an assault weapons ban and other sensitive measures through a Congress that is already busy preparing for fights over three looming fiscal deadlines and a debate over comprehensive immigration reform. The country's most powerful pro-gun lobby, the National Rifle Association, is already rejecting many of Obama's proposals as it insists on an absolute reading of the Constitution's Second Amendment-guaranteed right to possess and bear firearms. The group, which also represents a gun industry that since the Civil War has promoted a national gun culture, has long warned gun owners that Obama wants to take their guns away. The head of the National Rifle Association said the organization has no problem with tighter background checks of gun purchasers, another key Obama proposal. But David Keene told CBS that too much emphasis has been placed on banning certain firearms and said officials should focus instead on the “devastatingly broken mental health system in this country.” — AP