The Obama administration on Thursday evening rejected Senate Republicans request that the Department of Health and Human Services lift a so-called gag order on insurance companies that have been critical of Democratic efforts to reform health care.HHS spokesman Nicholas Papas said the department will continue its investigation into a mailer sent to seniors by Humana that Sen. Max Baucus (D-Mont.) has argued contains misleading information about his legislations impact on Medicare and Medicaid.Our department is committed to protecting Medicare beneficiaries and ensuring that their personal information is not used inappropriately. Seniors on Medicare should not be subjected to misleading information about their Medicare benefits. We have serious concerns that certain communications from a major insurance company violated CMS regulations and our investigation will continue, Papas said.The Centers for Medicare and Medicaid Services, a division of the HHS, launched its investigation earlier this week in a response to a request from Baucus. As part of its inquiry, the CMS sent a letter to Humana and other companies warning them against sending seniors the insure mailers claiming Baucus bill will reduce their benefits.Republicans have taken up the controversy, arguing that Humanas claims about potential reductions in benefits to Medicare are not misleading and are backed by findings of the Congressional Budget Office. One GOP aide points out that even the language of Humanas mailer mirrored the language the CBO used, particularly the fact that both said the legislation could reduce benefits.They said could, not would, could, which is the exact same word that CBO used in their analysis, the aide said.Republicans have also sought to make the flap the centerpiece of a broader attack on President Barack Obama and Democrats, accusing them of attempting to stifle dissent against their policy proposals, tying the Humana incident to charges of racism and astroturfing relating to the August town hall protests.Earlier Thursday, the entire Senate GOP leadership team Minority Leader Mitch McConnell (Ky.), Minority Whip Jon Kyl (Ariz.), Conference Chairman Lamar Alexander (Tenn.), Policy Committee Chairman John Thune (S.D.), Conference Vice Chairwoman Lisa Murkowski (Alaska) and National Republican Senatorial Committee Chairman John Cornyn (Texas) sent a letter to HHS Secretary Kathleen Sebelius demanding that she lift the gag order on the insurers and warned that they would filibuster all 10 remaining HHS nominations until the issue was resolved. McConnell and Kyl also appeared on various cable news shows Thursday evening to accuse the administration of seeking to curb First Amendment rights of insurers.Finance ranking member Chuck Grassley (R-Iowa) and Health, Education, Labor and Pensions ranking member Mike Enzi (R-Wyo.) also signed the letter, which came as Ways and Means ranking member David Camp (R-Mich.) and Minority Leader John Boehner (R-Ohio) were calling on House Democrats to get involved with the controversy.Democrats, however, have vigorously defended the CMS decision and sought to turn the controversy to their own purposes, arguing the GOPs defense of Humana is part of a broader pattern of Republicans backing insurance companies over consumers.