"This is an issue that I believe should be addressed legislatively, and not through executive order," said Democratic Sen. Kay Hagan of North Carolina.
"I, too, am frustrated with the partisanship in Washington," Sen. Mark Pryor (D., Ark.) said in a statement. "But that doesn't give the president carte blanche authority to sidestep Congress when he doesn't get his way."
Sen. Mark Begich (D., Alaska), another endangered incumbent, has expressed similar concerns directly to senior White House officials, an aide said. "To me, securing our borders has to be the priority, and that should be the president's focus," Mr. Begich said in a statement.
In Kentucky, Alison Lundergan Grimes, the Democrat hoping to unseat Republican Sen. Mitch McConnell, also has said Mr. Obama would be wrong to use executive orders to set immigration policy. Like the other Democrats, she blames the GOP for blocking legislation.
... for endangered senators, a sweeping move to protect undocumented immigrants poses problems, said a Democratic strategist working on Senate campaigns, because it puts immigration into the news in states where it is politically difficult to defend illegal immigrants.