The move, led by Republican senator Orin Hatch and Democratic senator John Kerry, urges that the deal be finalised as soon as possible to minimise the negative impact on both companies.
"The deal between Oracle and Sun was announced in April and seven months have gone by without a resolution. Continued delay of the European Commission's decision on clearance threatens thousands of American jobs, so we felt compelled to ask for a speedy resolution," said Kerry.
"The EC is within its sovereign rights to set the rules for operation in its market, but with our Department of Justice having made a compelling case that the merger does not pose a threat to competition, it is fair to ask the EC for the basis on which a delay on decision making is warranted, and to make a decision one way or the other."
The letter stresses that the US Department of Justice conducted a thorough investigation and cleared it with very little delay. There are also suggestions that the delay is politically motivated.
"I have become increasingly concerned about the growing body of evidence [suggesting] that foreign regulatory agencies are unfairly using their review processes to impede the business of American corporations," said Hatch.
"This transaction has been thoroughly reviewed by the US Department of Justice, which has decided to take no action. Therefore, I hope the EC will quickly conclude its investigation into this transaction."
However, Florian Mueller, a former MySQL shareholder, warned that the letter was nothing more than a lobbying ploy.
"In a regulatory process like this, resorting to lobbying is typically what companies do when they can't win on the substance of a case," he said.
"Apparently the Commission's Statement of Objections was much stronger than Oracle wanted to admit, so they asked some political friends for help. But I'm sure this will not change the outcome.
"It would have been a better idea for the 59 senators to send a letter to [Oracle chief executive] Larry Ellison, asking him to commit to divest MySQL so he can close the transaction quickly.
"Oracle always said that MySQL is small in terms of revenues and it's the only regulatory concern left in this whole process, so Oracle could have a deal any day of the week by giving up MySQL. If the senators really want to speed things up, that would be the right approach."
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