They are hoping that Juma Al Dossary and Isa Al Murbati will be released from the notorious prison in Cuba before Eid Al Fitr, which falls in October.
MPs Dr Jassim Hussain, Dr Ali Ahmed and Adel Al Asoumi were in Washington to take a course on drafting legislation.
However, they also used the trip to meet government officials, congressmen, Non-Governmental Organisations (NGOs) and others to highlight the plight of the Guantanamo Bay inmates.
Following their return, Dr Hussain accused Bahraini authorities of not doing enough to bring its citizens home – claiming that American NGOs are doing more than their own government to secure their release.
"Whether it is former MPs or us – everyone is trying to secure their release, except the government which is doing nothing," he told the GDN.
"The Foreign Ministry is not working hard enough and while other Arabs have been released, two out of six Bahraini detainees are still behind bars.
"We have good relations with the US, but we are not capitalising on them.
"Trying to get the two released before Eid Al Fitr, in October, has topped our agenda.
"However, we need the support of our government.
"We won’t rest until they are back with their families, who have waited long enough."
The four Bahrainis who have already been freed from Guantanamo Bay are Salah Abdulrasool Al Blooshi, Adel Kamel Hajee, Shaikh Salman bin Ebrahim Al Khalifa and Abdulla Majid Al Nuaimi.
However, Mr Hussain criticised the fact that others are still being held without charge over five years after they were captured.
He also questioned the validity of their detention for such a long time after their incarceration.
"It has been five years of waiting and nothing has been done," he said.
"Even if the detainees, whether Bahrainis or otherwise, are hiding anything – it would be outdated considering that intelligence changes by the second.
"There is no reason behind their detention, but I can’t blame the rest of the world – countries are taking a stand against the US for its numerous violations against human rights.
"Now, whenever the US tries stopping human rights violations in any other country, it is being told to fix its own status before approaching others."
Dr Hussain added that MPs would also work towards releasing two other Bahrainis from GCC jails.
They are Abdulraheem Al Murbati, held in Saudi Arabia for the past three years, and Adel Abdulkhaleq, arrested in the UAE in May.
"It is true that the two Bay detainees get priority in our negotiations due to the harsh conditions and the suffering they are going through, but this doesn’t mean that the two others – even though they are treated better – shouldn’t be given attention too," said Dr Hussain.
"All of our prisoners will be back home soon and we are currently negotiating with our GCC counterparts to help secure their release."
Foreign Ministry officials were unavailable for comment.