She also said she was "disappointed" President Barack Obama would not be visiting the annual conference of the National Council of La Raza in Las Vegas.
The gathering has "a long tradition of inviting candidates for president from both parties to join us," Janet Murguia told a luncheon audience of about 1,500 people.
"This year was no exception," she said. "We asked both President Obama and Gov. Romney to address us here in Las Vegas."
Every Democratic and Republican president and nominee since George H.W. Bush has addressed the conference.
"We are particularly disappointed that Gov. Romney is not with us," Murguia said. "We in the Latino community want to hear from the presumptive Republican presidential nominee on the issues we care about.
"And frankly we believe this is a major missed opportunity for him," she said to applause.
A Romney campaign representative in Las Vegas told United Press International Monday Romney didn't attend due to a scheduling conflict.
He was represented at the conference Saturday by former U.S. Commerce Secretary Carlos Gutierrez, one of his top Hispanic advisers.
NCLR said the agenda was full and didn't give Gutierrez a speaking slot. Gutierrez, who ran the Commerce Department in the George W. Bush administration, greeted people at a Romney campaign booth at a Latino expo that's part of the conference.
NCLR is "also disappointed that the president could not be here," Murguia said at Monday's luncheon.
Obama also has a scheduling conflict and is to be represented by Vice President Joe Biden, who is to address the conference Tuesday.
Murguia spoke about Obama's June 15 executive action to stop deporting some undocumented immigrants who were brought to the United States as children and later went on to be productive and otherwise law-abiding residents -- giving them a two-year reprieve but not granting them legal status.
She said the action accomplished two major changes.
"First, it gives up to 1 million people the chance for temporary legal status so that they can go to work or school or serve in the military without having to live in constant fear of deportation," she said. "And second, it puts the burden back on Congress to find a permanent solution, not only to this issue but also to enact comprehensive immigration reform."
Concerning the U.S. Supreme Court's landmark June 25 split decision rejecting much of Arizona's tough 2010 immigration law but upholding its hotly debated centerpiece -- called by critics the "show me your papers" provision -- Murguia vowed, "This law will not stand.
"It will not stand, not just because it is inherently wrong but because you and I will take it down," she said. "The demographic shifts transforming the country, especially in states like Arizona, make that outcome inevitable. And our vote will be our weapon."
She called on Hispanics to use their vote to "double down" against "the remnant" of Arizona's Senate Bill 1070 -- which empowers police to check the immigration status of anyone they stop if they have "reasonable suspicion" the person is in the United States unlawfully -- and to fight similar laws in other states that "divide, demean and deny people their basic humanity."
Such laws are inconsistent with U.S. "values of hope, equality, fairness and justice," she said.
"You want to ask us for our papers? You will find them in the election box this Election Day," she said.