Current sanctions have undercut the Iranian economy, causing high unemployment and inflation while daily oil production and the value of the country's currency, the rial, have dropped.
In the latest round of talks, the six world powers were unable to persuade Iran to limit its production and stockpiling of uranium enrichment to 20 percent and close its underground Fordo enrichment site.
Mark Dubowitz, a sanctions expert and executive director of the Foundation for Defense of Democracies, said lawmakers sense an imperative to act and ratchet up the pressure.
"I think everybody was waiting for this latest round in Almaty (Kazakhstan). Now that that's deemed to be a failure, Congress realizes that time is running out and clearly the current sanctions have not yet cracked the nuclear will of Iran's supreme leader," Dubowitz said.
The concern is that Iran is 15 months from an undetectable nuclear breakout yet has the sufficient foreign exchanges to last beyond that date.
"The question now is whether in that short period of time, the U.S. can massively intensify the sanctions and bring the regime to the brink of economic collapse before the regime achieves an undetectable nuclear breakout," he said.