A bipartisan group of senators is pushing President Obama to move forward with new sanctions against Iran, now that his “end of 2009” deadline for meaningful response from Tehran — which the administration insists was not a deadline — has long past.

Senior administration officials have said over and over that they are switching to the “pressure track” against the Iranian regime following an acknowledgment that the year-long “engagement track” effort has failed to produce measurable results.  The Senate is getting ready to bring up Chris Dodd‘s Iran sanctions bill, not waiting for the administration to be ready, causing some friction within the Democratic power structure.

On Wednesday, seven senators wrote to Obama to say that they’ve had enough of waiting for the pressure-track activities to begin.

“Now that this deadline has passed, we believe that it is imperative to put into action your pledge of increased, meaningful pressure against the Iranian regime — what Secretary Clinton called ‘crippling sanctions,'” the letter reads. “We believe it is important for the world to know that the United States means what it says, and that we in fact do what we say we are going to do.”

Multiple sources tell The Cable that the White House has made the decision to pursue a sanctions resolution at the U.N. Security Council and is busily working on that with European allies. Of course, the Chinese, who hold the council’s rotating presidency until the French take over next month, are not expected to go along. But at least if that effort fails, the thinking goes, the administration can claim it exhausted all diplomatic options before imposing unilateral sanctions.

The senators offered measured support for pursuing a new U.N. resolution, but doubted its success due to Chinese intransigence. “We fear that Beijing’s pursuit of its narrow commercial self interest in Iran is jeopardizing the chances for a diplomatic solution,” the senators wrote.

Accordingly, the senators want the White House to begin a parallel effort to use existing authorities under previously passed legislation to impose new sanctions. A revised National Intelligence Estimate on Iran’s nuclear program is expected soon, a potentially explosive document that could put new political pressure on the administration to act.

The letter was signed by Senate Minority Whip Jon Kyl, R-AZ, Joseph Lieberman, I-CT, John McCain, R-AZ, Evan Bayh, D-IN, Robert Casey, D-PA, Johnny Isakson, R-GA, Benjamin Cardin, D-MD, David Vitter, R-LA, and Charles Shumer, D-NY.