WASHINGTON (AP) — Four Republican senators say they are not ready to vote for the GOP health care bill, putting the measure in jeopardy.

The four are Ted Cruz of Texas, Ron Johnson of Wisconsin, Mike Lee of Utah and Rand Paul of Kentucky. They say in a statement that they are open to negotiation before the full Senate considers the measure.

The four say there are provisions that are an improvement to the current health care system. But they add that the measure fails to accomplish what they have promised to their constituents, "to repeal Obamacare and lower their health care costs."

GOP leaders hope to vote on the bill next week and can only afford two defections from the 52 Senate Republicans.