According to the VRA, it is a criminal offense to willfully intimidate or interfere with a person attempting to vote

New Mexico GOP Sued For Voter Intimidation

ACORN (Association of Community Organizations for Reform Now) has sent out a press release about a lawsuit against the New Mexico GOP after reports that minority voters in the state are being intimidated by party officials. The press release:
Lawsuits were filed today in U.S. Federal District Court, charging New Mexico Republicans with criminal violations of the U.S. Voting Rights Act.
The lawsuits stem from a series of attacks on new, minority voters in Albuquerque--many of whom were assisted in registering to vote by ACORN--that began with a press conference on October 16, led by State Representative Justine Fox-Young, in which Fox-Young claimed to have solid proof that individuals had illegally voted in the June, 2008 Democratic primary election. At the press conference, the Republican Party broke state law by distributing the voters' personal information in its press packets.

The second attack came after ACORN visited 9 of the 10 smeared voters and proved them to be legitimate. On October 22, a private investigator visited at least 3 of the voters, leaving them shaken, one in tears. LinkHere