Updated

House Republicans are facing heavy pressure from both sides of the immigration debate as they return to their home districts for August recess with no clear indication as to how they’ll vote on the issue.

The decision to pass comprehensive immigration reform has essentially been in the hands of the Republican-controlled House since the Democrat-led Senate passed such a bill in June.

House Republicans were under pressure before they even left their Capitol Hill offices to start the five-week recess, which is traditionally dedicated to face-to-face talks with hometown voters.

The American Federation of Government Employees sent a letter Tuesday to House lawmakers urging them not to work with senators on their “dangerous” bill.

Among the major concerns is that U.S. Citizenship and Immigration Services is not equipped to process the potential onslaught of new applications.

Another is that the Obama administration might implement immigration law passed by Congress “in a fashion of its own choosing,” considering that it bypassed Congress last summer by stopping the deportation of young, law-abiding immigrants brought to the United States illegally by their parents or others, the union letter suggests.

The Senate bill includes billions of dollars for border security, new workplace enforcement requirements, a revamped legal immigration system and a path to citizenship for the estimated 11 million immigrants living in the country illegally.

Many House Republicans oppose granting citizenship to people who crossed the border illegally or overstayed their visas. And GOP leaders have already rejected the Senate bill, instead proceeding with narrow, single-issue bills, starting with border security.

House Speaker John Boehner has said he wants a vote on immigration reform.

However, before leaving Washington, Republican leadership also appeared more focused on repealing or defunding ObamaCare, to perhaps avoid the rancorous kind of town-hall style meetings over health care that took place in summer 2009.

At least some House Republicans will still have to deal with the issue, considering Tea Party groups and pro-immigration groups plan to hold rallies on the issue in Virginia and elsewhere.

NumbersUSA, a nonprofit advocating smaller-scale immigration, told FoxNews.com that it is cosponsoring an August 12 rally in Richmond, Va., with Tea Party Patriots and Eagle Forum, and that other events are planned for at least Ohio and Texas.

Tea Party Patriots confirmed on Saturday there will be rallies and town hall style meetings and said details are forthcoming.

The National Council of La Raza, which supports large-scale immigration, purportedly said a coalition of groups will host more than 350 rallies across the country during the recess.

Immigration supporters staged a protest Thursday on Capitol Hill in which 41 activists were arrested and suggested the sit-in was a prelude to the planned events this month.

"When you want policymakers to see the light, sometimes you've got to raise the heat, and that's what we're doing today," said Frank Sharry, executive director of America's Voice, who was among those arrested.

Several Democratic lawmakers joined the marchers but did not participate in the civil disobedience. Rep. Raul Grijalva, D-Ariz., promised: "What is happening today is going to be repeated around the country."

Alabama Republican Sen. Jeff Session, among the strongest critics of the Senate bill, circulated a letter earlier this week that appeared to serve as a strategy memo for House Republicans this month.

“The GOP has a choice: It can either deliver President Obama his ultimate legislative triumph, and with it, a crushing hammer blow to working Americans that they will not soon forgive," wrote Sessions. “Or it can begin the essential drive to regain the trust of struggling Americans who have turned away. … This 1,200-page immigration bill is a legislative monstrosity.”

The Associated Press contributed to this report.