(A supporter of Islamist political party Jamaat-e-Islami backs Pakistan's blasphemy laws during a rally in Peshawar January 23, 2011/Fayaz Aziz )

Pakistan’s disparate Islamist political parties are uniting behind their hatred of the United States, emboldened by a weak government that looks increasingly reluctant to stand up to extremism and a society where radicalism is widely tolerated. The prospect of these parties gaining strength in this nuclear-armed nation is a nightmare for its ally the United States and neighbors including India and Afghanistan, which are already fighting Islamist insurgents based in Pakistan.

But while there is little chance Islamist parties will be able to take power outright, they are becoming more prominent as anti-Americanism grows among ordinary Pakistanis, many of whom also reject attempts to soften a blasphemy law that has claimed the lives of two senior officials this year alone.

“The government is struggling to respond to populist forces at precisely the moment when it aims to improve its position to secure a full term and better position itself for the 2013 elections,” wrote analyst Maria Kuusisto of consultancy Eurasia Group in a research note.

Islamists parties, who traditionally have done poorly at the polls, stand a better chance if elections are held nowadays, analysts said. And if they increase their numbers in parliament, they could force a new government to the right, shake the alliance with the United States, including ending cooperation against the war in Afghanistan, and push the government into concessions with Pakistani Taliban militants. Most of the parties support Afghanistan’s Taliban and they all want to enforce strict sharia law.