Sen. Rob Portman is targeting a deadly synthetic opioid in new legislation he plans to introduce when Congress returns next week.

The Ohio Republican's move comes a few days after Cincinnati reported 174 overdoses in six days potentially linked to the synthetic opioid fentanyl and another opioid called carfentanil. The bill is intended to help postal workers screen for and catch fentanyl that is being mailed into the U.S. from overseas.

Portman said his bill would help stop "synthetic drugs like fentanyl and cafentanil from coming into Ohio in the first place."

Fentanyl is a synthetic opioid that can be up to 100 times more potent than morphine. Federal data shows that overdoses of fentanyl are soaring.

The legislation would target imports from China and India, which are the primary source for illegally produced fentanyl and carfentanil.

Portman noted Wednesday that the drugs often enter the U.S. through mail couriers and then are distributed by traffickers across the U.S.

The U.S. Postal Service doesn't have screening tests to detect the drugs before they reach traffickers, he noted.

The legislation would require shippers from foreign countries using the postal system, which doesn't include private carriers UPS or FedEx, to provide electronic advance data before packages cross into the U.S. The information would include who and where it is coming from; who is getting the package, where it is going and what is in it. Getting the information can help give customs officials a leg up and better target potentially illegal packages.

Overdoses from fentanyl are soaring in the U.S., according to a recent study from the Centers for Disease Control and Prevention. Deaths from synthetic opioids increased by 79 percent from 2013 to 2014 for 27 states that the CDC examined.

Portman has made fighting opioids part of his re-election campaign, with ads highlighting his efforts to get the Comprehensive Addiction and Recovery Act approved. President Obama signed the legislation into law earlier this year.

The legislation seeks to expand access to the overdose antidote naloxone and broaden treatment options for addicts.

The RealClearPolitics polling average shows Portman with a seven-point advantage over former Gov. Ted Strickland.