Republicans who back immigration reform are ramping up their push to get the House to bring legislation to the floor, as the issue threatens to potentially create a public divide within the GOP.

The Wall Street Journal reports the group Republicans for Immigration Reform is building up its lobbying efforts in Washington, releasing a web ad last week urging the House to act that has been viewed over 600,000 times, according to the group.

This week, the New York Times reports a coalition of about 600 mostly Republican leaders in business and agriculture will begin an effort to lobby 80 GOP representatives on the issue. Some GOP donors are also reportedly privately withholding their contributions from members of Congress who oppose action of immigration reform.

The issue has the potential to divide GOP lawmakers again after public in-party fighting over the recent budget negotiations.