
(CNN) -- Pennsylvania Rep. Joe Sestak has informed supporters he plans to challenge Sen. Arlen Specter in the Democratic primary, a spokesman for the congressman tells CNN.
Jonathon Dworkin, Sestak's communications director, confirmed the authenticity of a handwritten letter from Sestak - first posted on the Web site Talking Points Memo - to a supporter in which the congressman states, "I intend to run for the U.S. Senate."
Dworkin also confirms quotes from Sestak's sister to TPM stating, "He intends to get in the race,..."In the not too distant future, he will sit down with his wife and daughter to make the final decision."
Sestak’s decision to challenge Specter, who recently switched his party affiliation from Republican to Democrat, puts the congressman at odds with Democratic congressional leaders and President Obama. The president and the congressional leaders have endorsed Specter for re-election in 2010.
Sestak will appear on CNN's The Situation Room to discuss the race at 6:45 p.m. EST.
Text of the letter:
"I am writing you as especially dear supporters to let you know I intend to run for the U.S. Senate...my candidacy's credibility will have much to do with my fundraising success by the 30 June FEC filing deadline at the end of this quarter. Would you help me bring the change for the future we Pennsylvanians need[?]"


Fabulous! This is great news!
Go Joe!
I think Specter is better, but my opinion won't decide the election..
Go for it dude. That's what elections are all about. I encourage anyone who wants to do public service to "just do it" either by elected office, volunteerism or political activism.
It's what we're about as Americans.
Good run!!! wonder what obama will do to try and shut you up, now that he wants or apparently promised specter he could run as a democrat unopposed.
Here we go again, who to vote for, since he would be my Senator.
Good! let a real Democrat run!
Don't know this guy, but hope he wins over that two timing Specter. Democrats deserve a real democrat, not a self serving phony.
GREAT!
It's time for that rich, dusty old white guy to move over and let the "new" blood into the Senate. At least we know Sestak is a true democrat not just one of convenience.
Besides, Sestak is a really, really smart former military guy – The dems need more of them...
Bye bye, Arlen... (hint: they'll probably pick a real democrat over an ambiguous one)
Specter is washed up.
Anybody notice how much this guy looks like John Kerry? I think they cloned him...
Hope you nail that self-serving,self-centered son-of-a-gun. Man could care less about the people he supposedly serves.
I was hoping Joe Sestak would do this. Good for him. We need a real Democrat to win in Pennsylvania, not one who sold his soul to salvage his political career.
Good, honest political competition never did anyone any harm. I am sure that the people of Pennsylvania will be the winners.
The IRA? What is a republic?
Oh wow, a corrupt incumbent against a corrupt challenger. Stop the presses!!!
So, Sleestak is going to go up against Sphincter. This will be a battle of epic proportions!
Where do I send my check?
Go Sestak!
This raises the specter of an interesting primary race. Looks like Arlen will face the consequences of not supporting Obama's program. How can voter be so stupid to believe Arlen needs one more term to accomplish his goals? Time to give someone else a chance to serve.
As a PA voter I urge , at this time, for Rep Sestak to cool it . Now is not the time for him to run...he will divide part thus giving the Reps a great chanc in the fall...Pres Obama supports Specter that says it all for me....
Pa Voter..
If Osama Bin Laden entered the democratic primary against Arlen Specter, I would send a donation and vote for him. Go Sestak.
Joe Sestak was the hardest workers I have ever met. I would vote for him .
hope Arlen is defeated !!!!!!
if obama is smart, he either steers clear of this race, or backs sestak. specter is dead weight to the democratic party. sestak is new blood. specter really has no money in the bank with obama. obama owes him nothing. specter only switched parties because he expects to lose the republican primary in pennsylvania. sestak is running as a democrat because he agrees with the principles of the party. i really hope obama does NOT blow this one.
Mr. Sestak – I wish you the VERY best of luck! I do hope you win your contest for the Democratic representative... however, you have some powerful enemies: Obama, Biden, Specter, DNC leadership, etc.
Sad when the entire DNC party wants to ordain the democratic candidate and not give voters a real choice.
But hey – that's "change you can believe in" ... right?