WASHINGTON — THE United States government is likely to shut down nonessential services tomorrow, after House Republicans voted before dawn yesterday to attach a one-year delay of President Obama’s health care law (and a repeal of a tax to pay for it) to legislation to keep the government running. The Democratic-led Senate is expected to refuse.

House Republicans also said last week that they would not agree to lift the debt ceiling unless implementation of the health law was delayed by one year. So the government is also headed toward a mid-October default on its debts — and a full-blown constitutional crisis.

Failure to raise the debt will force the president to break a law — the only question is which one.

The Constitution requires the president to spend what Congress has instructed him to spend, to raise only those taxes Congress has authorized him to impose and to borrow no more than Congress authorizes.

If President Obama spends what the law orders him to spend and collects the taxes Congress has authorized him to collect, then he must borrow more than Congress has authorized him to borrow. If the debt ceiling is not raised, he will have to violate one of these constitutional imperatives. Which should he choose?