A Republican senator from the U.S. state of Pennsylvania says the United States’ naval blockade and economic pressure on the Islamic Republic of Iran “are starting to take effect,” and that a new round of secondary sanctions could put additional pressure on Tehran and its trading partners.

“Don’t make any mistake; our economic blockade and pressure are starting to take effect,” David McCormick told CNBC.

The Republican senator, citing his own assessment of Iran’s economic situation, said Iran’s economy has shrunk by between 5 and 6 percent this year, inflation has reached around 70 percent, the value of the national currency has fallen by between 30 and 40 percent, and long lines for fuel have formed.

He added that a new round of proposed U.S. sanctions—especially secondary sanctions—“tightens the pressure ring,” because these steps put not only Iran, but also companies, banks, and the companies and countries that do business with the Islamic Republic at risk of punitive U.S. actions.