Interviews and job offers in the US

B

Hi everyone,

I am curently in the final months of my PhD, and I received an offer for a research position in the US. Even if this offer is attrative, I also wrote other applications and, actually, I would like to wait for some time to see what the outcome of these applications will be.

Does anyone have a clue long I can keep these people waiting without insulting them? Being a European, I am not sure about the American habits in this matter (it is a public research institute).
Furthermore, they only gave a me a "verbal offer"(on the phone) and no written letter. Is this customary? I asked them for a written offer (in an email) and they seemed to be a bit surprised....

Thanks a lot in advance,
B.

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