On January 3rd when the new Congress is sworn in, there will be 201 Democrats and 234 Republicans. If John Boehner is re-elected Speaker, he will likely continue to run the House according to the Hastert Rule. (See NYT series of postings, Debt Reckoning, see the posting at Dec 12 at 12:32pm.) The Hastert Rule means that the Republican Speaker will not bring to a vote any bill unless it has the support of a majority of Republicans.
Half of the 234 Republicans is 117, so the 117 most conservative members of the House, only 27% of the total House membership, can stop any compromise legislation that has been negotiated with the Senate and the White House. That’s why Boehner has such a hard time compromising with President Obama.