ABC News' Z. Byron Wolf reports: Senate Democrats today demanded that BP create a special $20 billion escrow account to pay for cleanup and liability from the Gulf of Mexico oil spill. Essentially, they say thanks to BP for admitting liability and promising to pay all “legitimate” claims, but, say the Senators, “history has taught us that corporations often fail to live up to their initial promises.” “After the Exxon Valdez tanker spilled more than 11 million gallons of oil into Alaska’s Prince William Sound, damages totaled more than $7 billion; although Exxon continued making massive profits after the accident, it fought liability at every step and ultimately paid far less than the billions of dollars worth of damages it had caused many, many years later,” write the Senators. There are 55 signatures on the letter (of a total 59 Democratic Senators). Republican staffers did not dismiss the idea of a special trust fund, but said there were no Republican signatures on the letter because they were not asked by Democrats to sign on. Democrats in the Senate, led by Sen. Bob Menendez, D-NJ, have repeatedly tried to raise the cap from $75 million, first to $10 billion and more recently to unlimited liability. BP has said it will ignore the cap and pay all legitimate claims. Republicans in the Senate have objected to Democrats proposal to lift the liability cap altogether. Sen. David Vitter, who made the objection against lifting the cap for all oil companies, arguing that the $10 billion figure was based on guesswork, endorsed specifically targeting BP, lifting the cap on liability, but just for BP.