Investors are worried the risk of default for US local governments is growing, amid signs that some regions are facing the same type of difficulty in curbing pension and budget deficits as some euro zone countries.

The yield attached to some forms of infrastructure municipal bonds has risen sharply relative to US Treasury bonds because of fears that cash-strapped local governments will struggle to repay these loans.

Absolute borrowing costs for regional governments remain relatively low in historical terms because of the Federal Reserve’s ultra-loose monetary policy. But the swing in municipal yields will be watched closely by investors, since it suggests that the fiscal anxieties about the euro zone could now infect the United States.

“The risk in the second half of the year is that investor attention switches from Europe to the US,” said Robert Parker, senior adviser at Credit Suisse Securities.