Recently Brett Sherman was nominated to chair of Investor Protection, Entrepreneurship and Capital Markets. He will surely have the power to influence bills that can get introduced into Congress. He has been incredibly anti-bitcoin and will surely try to pass bills that will stifle the growth of the industry.
No matter how hard they try to stop Bitcoin its always going to succeed and thats the truth. I know for sure that there will be countries that will try to stop their citizens from making use of Bitcoin, but not every country will do that, there are already a lot of them that are in support of Bitcoin. So, even if others tries to stop the use of bitcoin, there will still be others that are strongly promoting it.
I think they can't stop the usage of bitcoin. The only thing that will make it stop is when they propose a law regarding the usage of the bitcoin.
This is not the first time Im seeing people talk about stopping Bitcoin, it has been said a lot of times but one thing I know for sure is that thats never going to happen. Regulations and laws against using bitcoin may stop people temporarily as adopting bitcoins and using it can be done highly anonymously like without letting your IPS or colleague or spouse knowing what you do.