Republican lawmakers are preparing to introduce legislation to direct the U.S. Treasury to make interest payments on U.S. bonds first and then prioritize other government outlays in case Congress does not raise the debt ceiling.

Supporters of the idea see it as a politically palatable alternative to default, which could rattle markets as occurred in the summer of 2011. The likelihood of another market-unsettling event is challenging Republicans to find another idea as they use the debt ceiling as leverage to extract spending cuts from President Barack Obama.

But critics, including some Republicans, say prioritizing payments is largely unworkable and would not fool the markets. …

Among those advocating the approach is Republican Senator Pat Toomey of Pennsylvania, who is expected to reintroduce legislation next week to instruct the Treasury to make sure bondholders got paid first if Congress does not raise the debt ceiling by the deadline.