* Pfizer may delay any new bid until after meeting UK lawmakers
* State governors worried about losing American jobs
* Any Pfizer promises must be "ones that will stick" - Clegg
* Collapse of ad agency merger a different case - source
By Ben Hirschler
LONDON, May 9 (Reuters) - U.S. drugmaker Pfizer is under fire on both sides of the Atlantic as it weighs its next move to buy British rival AstraZeneca, which could be a sweetened offer next week.
A strategic question for Pfizer and its advisers is whether to come back with a new bid before bosses from both companies are grilled by UK lawmakers on May 13-14, or wait until the end of the week.
Two people familiar with the matter said on Friday it would be more "polite" for Pfizer to explain its current position to the two parliamentary committees before pushing out a new offer.
The New York-based company's record of slashing jobs after a string of earlier mergers has provoked a political backlash against the proposed $106 billion takeover at home and in Britain, with two U.S. state governors joining the fray on Thursday.
Maryland Governor Martin O'Malley and Delaware Governor Jack Markell wrote to Pfizer Chief Executive Officer Ian Read "expressing deep concerns" about the planned deal, given the fact that AstraZeneca employs 5,700 people in the two states.
Many in the United States fear Pfizer's promise to Britain that the combined company would keep 20 percent of its research and development workforce in the country will inevitably jeopardise American jobs.
It is the same fear that agitates politicians in Sweden, where Prime Minister Fredrik Reinfeldt said his country had already had "negative experiences" with Pfizer after it failed to honour promises on jobs following its 2002 acquisition of Pharmacia.
In Britain, however, there are concerns that Pfizer's vows leave too much room for it to renege on its promises, and Prime Minister David Cameron, who initially welcomed Pfizer's "robust" assurances, now wants more commitments.
Deputy Prime Minister Nick Clegg said on Friday that the government needed to be confident about any such promises. "Our focus is to make sure that, if the companies decide to proceed, the commitments ... are serious ones, are durable ones, and are ones that will stick," he said at a Reuters newsmaker event in London.
There is also growing disquiet about Pfizer's desire to reincorporate in Britain to cut its tax bill, with U.S. Democratic senators weighing legislation to prevent such tax "inversions".
AstraZeneca has rejected successive approaches from its larger American rival and Chief Executive Pascal Soriot is now on a roadshow with advisers to meet dozens of leading investors and lay out his strategy for a prosperous independent future.
Soriot has secured the backing of several high-profile shareholders but others have told Reuters they would like him to engage with Pfizer if the U.S. group makes an improved offer.
Shares in AstraZeneca, which rallied nearly 2 percent on Thursday on talk that an improved bid might be imminent, fell back 1.8 percent on Friday afternoon.
"I can't see there being much movement from these levels until there's more clarity on Pfizer's intentions," said Central Markets trading analyst Joe Neighbour.
The collapse of a $35 billion merger between advertising giants Omnicom and Publicis has added some uncertainty around the proposed giant pharmaceutical deal.
The Omnicom-Publicis tie-up would also have involved an advantageous change of tax residence but faced a series of problems, including anti-trust hurdles in China, which may also snag Pfizer.
The deals are, however, fundamentally different. The two ad agencies sought a merger of equals, leading to feuding over top executive roles, while Pfizer's move on AstraZeneca would be a straight takeover.
"People will look for links but the reality is there isn't any real read-across on points of substance," said one person familiar with Pfizer's thinking. "Large mergers are difficult but every deal of this size brings its own issues." (Additional reporting by Sudip Kar-Gupta, Guy Faulconbridge and William James; editing by David Stamp)