WASHINGTON — Conservative lawmakers from five state legislatures launched a joint campaign on Wednesday to try to cancel automatic United States citizenship for the American-born children of illegal immigrants.

At a news conference here, Republican legislators unveiled two model measures they said would be introduced in at least 14 states. One was a bill clarifying the terms of citizenship in those states to exclude babies born here of illegal immigrant parents. The second was a compact between states to adopt common positions on the issue.

The lawmakers acknowledged that the state bills were not likely to have a practical impact anytime soon, since they would be quickly challenged as unconstitutional. But the legislators — from Arizona, Georgia, Oklahoma, Pennsylvania and South Carolina — said they chose the inaugural day of a new, Republican-controlled House of Representatives to open the first round of litigation they hope will lead to the Supreme Court and also spur action by lawmakers in Washington.

“We are here to send a very public message to Congress,” said Daryl Metcalfe, a Republican state representative from Pennsylvania. “We want to bring an end to the illegal alien invasion that is having such a negative impact on our states.”

The state lawmakers’ initiative put the highly emotional issue of birthright citizenship, which had long been marginal in the immigration debate, at the front of the Republicans’ immigration agenda as the new Congress gets under way.

In a separate effort, Representative Steve King of Iowa, a Republican who will be chairman of the House Judiciary subcommittee on immigration, said he would introduce on Wednesday, as soon as the new House members are sworn in, a bill to eliminate birthright citizenship for children of illegal immigrants.

The right to United States citizenship for everyone born on American soil is described in the 14th amendment to the Constitution. The state legislators argued that certain phrases in the amendment signal that it was not intended to apply to children of immigrants who do not have lawful status.

Opponents of changing the status quo argue that determining American citizenship is clearly a federal matter in which states have no legal role.

Challenges, both legal and political, arose even before the state lawmakers had finished speaking. The news conference was interrupted four times by protesters who stood up to accuse the legislators of intolerance and racism. One protester cited the words welcoming immigrants from the Statue of Liberty.

Also on Wednesday, African-American, Latino and immigrant civil rights groups announced the formation of a new coalition they said was ready to defend the current interpretation of the Constitution in the courts.

“We will challenge any law that erodes the constitutional guarantee of citizenship,” said Lucas Guttentag, director of the immigrants’ rights project of the American Civil Liberties Union, one group in the coalition, which also included the NAACP and the Leadership Conference on Civil and Human Rights. “We believe these laws cannot survive constitutional scrutiny,” he said.

Copyright 2011 The New Times Company. Reprinted from The New York Times, National, of Wednesday, January 5, 2010.