I believe the Supremes have ruled that the government cannot restrict commercial speech in a pre-emptive manner and can only guard against fraud, or exposure of children to adult material. It stated that advertising is speech as defined by the first amendment, but that the 'shouting fire in a crowded theater' type of limits did apply.
Now, what constitutes 'political advertising' as against political blogging or just plain political speech? If you blog that Joe is a good candidate, that's ok; but if I print it on paper and mail it, it's 'advertising' and not ok?
At one point, certain organizations could talk about the issues, but had to be real careful when talking about which candidates sat on which side of which issue, to avoid suggesting that one candidate was better than the other. Now, even speaking about the issues is limited.
Can you really distinguish between political speech and political advertising? What would you use to decide that something is political advertising and not protected political speech? Since politics in the USA involves elections, anything talking about elections is political speech, is it not?
I think of advertising as paying money to place your promotion in someone else's media. That seems to me to be distinct from politcal speech.