Shouted protests punctuate Senate immigration hearing WASHINGTON -- A Republican senator shouted in protest Monday as a top Democrat complained at a Senate hearing that opponents of immigration reform were improperly using the Boston bombing as a reason to delay changes to immigration law. Sen. Charles Grassley of Iowa, the top Republican on the Senate Judiciary Committee, objected when Sen. Charles E. Schumer (D-N.Y.) singled out those "who were pointing to what happened -- the terrible tragedy in Boston -- as, I would say, an excuse for not doing a bill or delaying it many months or years." I never said that. I never said that," Grassley shouted. "I didn't say you did, sir," Schumer replied. "I didn't say anything about delaying the bill," Grassley insisted. Republicans, including Grassley, have linked questions about the immigration status of Dzokhar and Tamerlan Tsarnaev to what they describe as the need to move carefully on the immigration overhaul. The two suspected bombers, of Chechen origins, emigrated from Russia as youngsters a decade ago. Their family sought political asylum. Dzhokhar Tsarnaev, 19, who was naturalized as a U.S. citizen on Sept. 11, 2012, remains hospitalized following the manhunt that led to his capture. Tamerlan Tsarnaev, who died last week after a shootout with police, had a citizenship application pending. The heated exchange between the senators offered an unusually vivid display of the emotions generated by immigration reform, a complicated issue that has divided the Republican Party. Backed by a long list of business, labor and religious groups, a group of eight senators -- four Republicans and four Democrats -- proposed a sweeping immigration overhaul last week. As the 844-page bill begins its journey through the legislative process, Judiciary Committee Chairman Patrick Leahy (D-Vt.) promised a full debate. The committee will have an "open process on this," he said, banging his gavel to restore order in the packed committee room. There will be debate in the committee. We will have time for it. At the start of the hearing, Leahy had noted that linking the bombings in Boston to the reform effort "troubled" him. "Let no one be so cruel as to try to use the heinous acts of these two young men last week to derail the dreams and futures of millions of hardworking people," Leahy said. I urge restraint. Schumer said the bill can be amended during the expected monthlong committee debate in May. "If there are things that come up as a result of what happened in Boston that require improvement, let's add them to the bill," Schumer said. Certainly our bill tightens up things that would make a Boston less likely. But signs of GOP discontent continued Monday as another prominent Republican, Sen. Rand Paul of Kentucky, suggested that the bombings exposed gaps in the nation's immigration policy that the bill must address. "We should not proceed until we understand the specific failures of our immigration system," Paul wrote in a letter to Senate Majority Leader Harry Reid (D-Nev.). "Why did the current system allow two individuals to immigrate to the United States from the Chechen Republic in Russia, an area known as a hotbed of Islamic extremism," he asked. His question incorrectly recounted the migration route of the Tsarnaev family, which did not live in Chechnya, but in other parts of Russia and neighboring Kyrgyzstan. Were there any safeguards? Could this have been prevented?" he went on to ask. Does the immigration reform before us address this? Paul also questioned whether the U.S. should consider suspending student visas. Twitter/@lisamascaroindc