Conservative groups in the United States have launched an online drive to win support for a bill that would deny citizenship to children born on U.S. soil to undocumented parents.

The measure, known as the Birthright Citizenship Act of 2013 and introduced on Jan. 3 by Republican Rep. Steve King, establishes that citizenship may only be granted if one of the parents is a U.S. national or legal resident or if at least one of the two is undocumented but serving in the U.S. Armed Forces.

Birthright citizenship is enshrined in the 14th Amendment to the U.S. Constitution.

The proposed legislation is backed by groups such as Californians for Population Stabilization, which is trying to drum up support for the measure.

"Our current policy encourages women to enter the United States illegally so that they can gain citizenship for these 'anchor babies,'" CAPS said in an action alert on its Web site.

It added that the Department of Homeland Security is "reluctant to deport the illegal alien parents of a child born here."

VDare.com and NumbersUSA.com are two other groups that are trying to garner support for the bill, the first on immigration in the 113th Congress.

The purpose of King's bill is to amend "section 301 of the Immigration and Nationality Act to clarify those classes of individuals born in the United States who are nationals and citizens of the United States at birth."

Hispanic activists in Iowa - King's home state - have come out strongly against the initiative, which was previously introduced in 2011 but was stalled in a House of Representatives committee.

"The future of the United States depends on our children. We have to accept them and educate them. Congressman Steve King is divorced from reality," activist Ila R. Plascencia, of the League of United Latin American Citizens in Des Moines, Iowa, told Efe.

Plascencia noted that Hispanics are the country's fastest-growing minority and that the country's future depends on that community's development.

The bill was introduced two months after President Barack Obama won re-election thanks in part to 70 percent support among Hispanic voters, a whopping margin that has led many Republicans to reassess their hard-line stance on the illegal immigration issue. EFE