WASHINGTON - A bipartisan immigration bill narrowly survived a potentially fatal challenge on Wednesday when the Senate turned back a Republican bid to limit the illegal immigrants who could gain lawful status. The close vote on a proposal by Sen. John Cornyn (news, bio, voting record), R-Texas, to bar felons — including those court-ordered to be deported — from legalization reflected the delicate position of the contentious immigration bill, which remains under threat from the right and the left. The vote was 51-46 against the amendment. Democrats succeeded in sucking support from Cornyn's proposal by winning adoption of a rival...