WASHINGTON — Senator Ted Cruz, who once led a government shutdown in his efforts to defund President Obama’s health care law, has turned his sights on a more obscure target: the federal government’s plan to end its oversight of the internet’s master directory of website addresses.

The Republican from Texas does not appear to have the ability to inspire another insurgency so close to an election that will determine control of the Senate. He may not have the interest either. His technical theories about the registration of domain names — the “.net” and “.world” suffixes of internet addresses — have been discredited by engineers.

But his move to block the Obama administration through a short-term spending bill needed to keep the government open past Sept. 30 demonstrates that the former Republican presidential candidate remains eager to keep his name in lights, even at the expense of his colleagues’ efforts to get back to the campaign trail.

“I am hopeful and optimistic that leadership will follow through and protect the internet,” Mr. Cruz said on Thursday, when asked if he would prevent the short-term spending measure from moving forward without his internet provision.