Gov. Edward G. Rendell of Pennsylvania just accused the campaign of Senator John McCain and Gov. Sarah Palin of flat-out “lying” about Senator Barack Obama’s plan on taxes.

Mr. Obama would cut taxes for the majority of Americans, according to theTax Policy Center that has examined his proposals, and yet the McCain campaign continues to say that Mr. Obama would raise them.

“I call on Senator McCain to stop misleading, stop lying, about Senator Obama’s tax plan,” Mr. Rendell said in a conference call with reporters.

Politicians rarely accuse each other of lying, preferring euphemisms instead. Mr. Rendell’s unusually blunt language is a sign of the anger that Democrats are feeling as they watch the McCain camp distort Mr. Obama’s proposals (Factcheck.org says the McCain campaign is engaging in “a pattern of deceit”) and their frustration at being unable to stop it. Governor Rendell was highlighting the issue in advance of a visit Tuesday to Pennsylvania by Mr. McCain and Ms. Palin.

Mr. Rendell repeated his accusation several times. He said that most speakers at the Republican convention in St. Paul last week had “lied” about Mr. Obama’s tax plans and that Mr. McCain’s television ads “have continued to lie.” He said Mr. McCain was using “the big lie strategy,” which is to repeat something often enough in hopes that it will stick. And, he lamented, “to some extent it has stuck.”

The McCain campaign had no immediate response to Mr. Rendell’s characterization, but we’ll post it as soon as we receive one.

Update: A new Obama television commercial also suggests that the McCain/Palin ticket is “lying.”

It says that the two Republicans are not really the mavericks they claim to be. On the screen at the end are the words “A Naked Lie,” attributed to an article in The New Republic, as the announcer asks, “Politicians lying about their records?”

The new ad, combined with Mr. Rendell’s remarks, suggest a new aggressiveness by the Obama camp in trying to beat back the Republicans’ message, with the outright assertion that they are lying. Mr. Rendell hinted at the reason for this approach: the Republican message is gaining some traction.