It's no surprise that the Google hit for "March 25 Coalition" pulls up the Marxist-Leninist vanguard page for International ANSWER, the American left's main hardline communist organization.ANSWER has communist and socialist organizations involved in the coalition, along with rights groups, environmental groups, religious groups, and other social and political groups. While I don't agree with everything every group stands for, I believe it's possible to work together toward a common purpose, even with people with whom you do not agree 100% on every issue. I do not fear people who believe different things than I do, whether they be Republicans, Methodists, Communists, or homosexuals. I understand why folks on the right wish to demonize people with this guilt by association nonsense, but that doesn't make it any less contrived and phony.
Please contact your Member of Congress at this link if the anti-American activities of these groups bother you.
Here in America, it's ok to disagree with and dissent from our federal and state government, as well as from one or even both of the major political parties. While it's not mainstream, being a registered member of the American Communist Party (or a Muslim, or a Unitarian, or a Socialist, or a Libertarian, or...) is not anti-American.