ABC won't run health care ad because it is "partisan"

ABC can run an informercial from the White House promoting Obama health care plan, but they can't run an ad that is critical of the proposal? Here is my question: why does opposition mean partisan? After all, there are Democrats who oppose the bill also. A copy of the ad is below. From Fox News:

The refusal by ABC and NBC to run a national ad critical of President Obama's health care reform plan is raising questions from the group behind the spot -- particularly in light of ABC's health care special aired in prime time last June and hosted at the White House.

The 33-second ad by the League of American Voters, which features a neurosurgeon who warns that a government-run health care system will lead to the rationing of procedures and medicine, began airing two weeks ago on local affiliates of ABC, NBC, FOX and CBS. On a national level, however, ABC and NBC have refused to run the spot in its present form.

"It's a powerful ad," said Bob Adams, executive director of the League of American Voters, a national nonprofit group with 15,000 members who advocate individual liberty and government accountability. "It tells the truth and it really highlights one of the biggest vulnerabilities and problems with this proposed legislation, which is it rations health care and disproportionately will decimate the quality of health care for seniors."

Adams said the advertisement is running on local network affiliates in states like Louisiana, Arkansas, Maine and Pennsylvania. But although CBS has approved the ad for national distribution and talks are ongoing with FOX, NBC has questioned some of the ad's facts while ABC has labeled it "partisan." . . .

Adams objects to ABC's assertion that his group's position is partisan.

"It's a position that we would argue a vast majority of Americans stand behind," he said. "Obviously, it's a message that ABC and the Obama administration haven't received yet." . . .

BACKGROUND: ABC also refused to run an ad from the Republican party during the ABC News special from the White House on health care.

Opposition to health care isn't just limited to Republicans:

Fox/Opinion Dynamics poll said "the health care reform legislation being considered right now" is opposed by 21% of Democrats, 50% of Independents, and 81% of Republicans. Only 37% of Democrats and 15% of Independents think their families would be better off if it passed. . . .

As to the ads content, see this by Robert Samuelson.