Despite Republicans' repeated claims to the contrary, the Department of Homeland Security insists, "We are not engaged in a 'backdoor' amnesty."

On Tuesday, several Senate Republicans, led by Chuck Grassley of Iowa, wrote at least their fifth related letter in four months to the Obama administration, demanding answers about the U.S. government's plans to address illegal immigration.

"We write to you again to express our growing concern about the Department of Homeland Security's execution of U.S. immigration laws," said the letter, sent to Homeland Security Secretary Janet Napolitano.

The letter referenced several recently-disclosed DHS documents, including a U.S. Citizenship and Immigration Services draft memo outlining "administrative alternatives to comprehensive immigration reform," an Immigration and Customs Enforcement draft memo seeking public comment on detention policy, and an internal DHS memo assessing “"administrative options” and their political benefits.

"Whether or not the proposals ... have been officially implemented, it is increasingly clear that this Administration is following the spirit of these proposals by dramatically narrowing its efforts to remove whole classes of illegal immigrants," the letter said.

DHS officials took issue with that assessment, saying the department is "doing more than ever before to enforce U.S. immigration laws" and the "record-breaking enforcement statistics speak for themselves."

Led by ICE, DHS removed "more aliens in 2009 than in any prior year in the agency's history," and the department is "already surpassing records for criminal alien removals in 2010," DHS spokesman Matt Chandler said in a statement.

"[We] are on pace to place more people in immigration proceedings this year than ever before," the statement said.

In addition, DHS officials have said the USCIS and ICE draft memos are being taken out of context and distorted.

After Grassley's office provided the USCIS draft memo to media outlets in late July, Napolitano insisted it did not reflect "official policy or decisions" and was only intended to "elevate ideas" and "weed out" poor options. A DHS official told Fox News at the time that the draft memo was never signed by its authors and was never sent to the intended recipient, USCIS Director Alejandro Mayorkas.

Similarly, the ICE draft memo, which says in part that immigration officers "should not" detain "an alien charged only with a traffic-related misdemeanor" if that person is not a threat to public safety, was intended to begin a discussion and reflects the need for ICE to prioritize its efforts and resources, according to DHS officials. One DHS official said illegal aliens who are stopped for traffic violations would be placed into the removal process, with at least an order to appear in court, but not all illegal aliens can be detained pending their court appearances.

The ICE memo is labeled "Draft Only For Discussion and Comment," and it was made public in early August when ICE posted the memo on its web site, saying it was “not a final policy" and " disseminated solely to collect feedback" from the public.

In their letter to Napolitano, the group of Republicans also referenced a separate ICE memo, which they said “would effectively require state and local authorities to release illegal aliens if the alien's only violation is his or her illegal status." In that memo, posted on ICE's web site in late August, ICE Assistant Secretary John Morton issued new "Guidance Regarding the Handling of Removal Proceedings of Aliens with Pending Applications or Petitions," including consideration of dismissing cases in which the "alien appears eligible for relief as a matter of law and in the exercise of discretion."

A DHS official insisted the new guidance is intended to "clear the docket" of cases where defendants are "likely to get favorable" outcomes and be "granted status anyway," so "we have the space to go after" dangerous and other high-priority illegal immigrants.

Republicans, however, said such assurances "do not address the other proposals contained in these recently-discovered memoranda that would, among other things, evade the current statutory penalties that bar aliens who illegally cross our borders from receiving immigration benefits, or that would allow violators of U.S. immigration laws to use relationships to legal residents or U.S. citizens to obtain immigration benefits to which they are not entitled under the law."

"Your assurances also fail to address reports that DHS has adopted a policy of refusing to remove any illegal immigrant who happens to be apprehended if he or she might qualify for relief in legislation that has been introduced, but not passed, by Congress," the letter to Napolitano said.

Asked about the "other proposals" mentioned in the DHS documents and recent reports about DHS policy, Chandler, the DHS spokesman, sent Fox News his statement, insisting, "As we have said repeatedly, DHS will not grant deferred action or humanitarian parole to the nation's illegal immigrant population."

Meanwhile, also on Tuesday, Senate Republicans blocked efforts by Democrats to help some children of illegal immigrants become citizens. Senate Democrats were hoping to attach the so-called "DREAM Act" to a defense-related bill, but a Republican filibuster killed any legislation tied to the bill.