Clearly, yes, no senator planning on a "no" vote would be swayed by a flamboyant pop star, but I don't think that's her intent (she is, incredibly, somewhat smart). Gaga has an immense following...the biggest on Facebook and Twitter, I believe, more than our POTUS or anyone else. That following consists largely of young social liberals, a ton of soon to be first time voters - a constituency historically difficult to mobilize politically in any effective way (e.g. Voting) and will have enormous electoral power when they wake up and smell the bull-plop. That is the audience Gaga is playing to; notice it wasn't "I'm calling Snowe so she'll change her mind," it was "YOU need to call Snowe...look, I will too!"
Far from thinking Gaga ought to back off, "can it" or whatever euphemism detractors may think up, it's rather important, if we agree that a politically energized and/or mobilized Millennial generation is a good thing and is requisite for the country to move in any kind of progressive direction, that this constituency sees something coming of Gaga's - and, therefore, their own - efforts. Something older generations need to understand about the Millennials' mindset is that they (well, we, as this Gen X/Millennial border child shares this quality with the latter) require some indication early on when undertaking an effort toward a desired end that their labor is proving successful - rather than carrying the risk of expending energy that might later prove to have been in vain.
I need hardly point out how quick many folks are to dismiss pop music and musicians for (supposedly) being all about recreation and frivolity when this is a world of serious matters and overwhelming injustices, only to scoff and sneer when an entertainer does try to venture beyond those decadent confines to try and take a social or political action. Kathy Griffin put it wonderfully on Twitter last night: in response to a follower's question ("r u mad Gaga stole ur DADT thunder?") the fiery comedian responded, "Neither of us r gay service members, so u LOVE her thunder." (sic) It is increasingly clear that the America of tomorrow, the one the progressive Millennials will inherit and inhabit, is under attack by a frighteningly stubborn conservative political wing and the idiots that follow their every untruth, and the other side has immensely powerful and influential generals commanding its troops, from Sarah Palin to Glenn Beck to Rush Limbaugh. Lady Gaga is perhaps one of the only figures with that kind of level of influence on our side, and we should rejoice in her willingness to take up the fight.
If anyone understands and respects the power of the masses it's Lady Gaga. We ought to respect and support when a superstar understands that her own power is nothing compared to the collective power of the multitudes who look up to her. The Civil Rights movement had great musicians providing the score; why shouldn't the gay rights movement advance to the beat of Lady Gaga?