The Obama administration is dispatching a top Cabinet official on a two-day tour of the southwest border with Mexico amid calls from Republicans for stricter controls on illegal migrants as part of a potential deal to overhaul immigration laws.

Janet Napolitano Homeland Security Secretary Janet Napolitano (Mandel Ngan -- AFP/Getty Images)

Homeland Security Secretary Janet Napolitano will visit San Diego on Monday and El Paso, Tex., on Tuesday to review border security operations and meet with state and local officials and other stakeholders.

The trip comes in the wake of comprehensive immigration reform proposals last week from both President Obama and a bipartisan Senate working group that include strengthening security along the border. Some Republicans, including Sen. Marco Rubio (R-Fla.) and Sen. John McCain (R-Ariz.), have said they will not support a path to citizenship for the nation’s 11 million illegal immigrants until stricter border controls have been implemented -- a red line that has quickly emerged as a major obstacle for a potential agreement.

White House officials and immigration advocates argue that the administration is spending more money than ever to protect the border, and they cite statistics showing that the flow of undocumented migrants has slowed.

Several high-profile studies have found that the federal response has helped reduce the flow of illegal immigrants, bringing net migration between the United States and Mexico to a virtual standstill.

Last year, the government spent $18 billion on immigration control, 24 percent more than all other federal law enforcement agencies combined, according to a study released this month by the nonpartisan Migration Policy Institute. The Obama administration deported nearly 410,000 people in 2012 — a record, and 25 percent more than in 2007.

At the same time, the number of people apprehended at the Mexican border trying to enter the United States dropped to 340,000, a 40-year low, in 2011. Immigration advocates say the decline shows that the heavy investment in border agents and surveillance technology has effectively deterred foreign nationals from attempting to cross.

Republicans argue that as the U.S. economy improves, the flow of undocumented workers is likely to pick up again. And they cite a report last month from the Government Accountability Office that determined that the U.S. Border Patrol was intercepting just 61 percent of migrants who attempted to cross illegally into the country from Mexico.

Napolitano is scheduled to speak with reporters at the U.S. Coast Guard District Maritime Unified Command in San Diego on Monday, and at the U.S. Customs and Border Protection office in El Paso on Tuesday. She will meet with Cecilia Munoz, White House director of domestic policy, when she returns from her trip, officials said.