The Boston Marathon bombings exposed not only the vulnerabilities of one of the nation’s iconic sporting events, but also the new limitations of one of its most iconic political institutions: the Massachusetts congressional delegation.

That much was clear when the state’s leading political and law enforcement figures assembled for Tuesday’s morning-after news conference. Speaking for the largest all-Democratic delegation at the Capitol was the state’s senior senator, Elizabeth Warren, who hasn’t been in office for even 15 weeks. She felt compelled to use her moment at the podium to assert that no clout was needed from her at a time like this.

“We did not have to reach out to the president,” she volunteered. “The president reached out to us.”

Standing silently by Warren’s side was the junior senator, William “Mo” Cowan, the appointed answer to a future political trivia question. His five-month sinecure will be over in June.

Also in the tableau — also with a non-speaking part, but delighted at the free publicity — was Stephen F. Lynch of South Boston, who will probably be just another House backbencher in a few weeks, assuming his uphill campaign for the Senate ends in a primary loss to delegation dean Edward J. Markey.

That group shot perfectly illustrates the dramatic, and objectively measurable, decline in the Bay State’s historic sway in Washington.

Massachusetts has had inordinate influence in the federal government since the birth of the Republic, of course. It’s spawned a series of political dynasties, starting with the Adamses in the 18^th century, and produced two of the more influential House speakers of postwar period in John McCormack and Tip O’Neill.

So it’s little surprise that the state finished seventh in delegation clout back in 1990, when Roll Call first devised its formula for assessing each delegation’s measure of potential influence in each new Congress. And, even though the ranking system favors the most populous states, Massachusetts routinely punched well above its weight and finished in the top 10 in all the subsequent rankings.

Until this year.

The delegation’s stroke peaked at No. 6 four springtimes ago, when the ailing Ted Kennedy was second in Senate seniority and remained chairman of the Health, Education, Labor and Pensions Committee; John Kerry was in his 25^th year as a senator and had just claimed the Foreign Relations gavel; Rep. Barney Frank was in his second term as Financial Services chairman and his House colleagues were in charge of subcommittees on Appropriations, Ways and Means and six other panels.

With Kennedy gone and the House under GOP control, the state slipped to No. 9 two years ago.

And now? The delegation’s expected ability to throw its relative weight around has dropped through the floor to No. 20 among all the state teams at the Capitol and to No. 35 in the clout-per-member measurement, according to the Roll Call Clout Index for the 113^th Congress, which will be unveiled in a few days. (Here’s a sneak peak.)

At first glance, it’s a wonder the ranking remains that high, even though at 6.6 million Massachusetts remains 14^th in population. Not only does the state lack any Senate seniority at all, but its all-Democratic delegation on the other side of the Capitol means no gavels or leadership posts in the Republican House, either.

Although those nine House lawmakers have a decent amount of combined seniority, the only ranking member of a full committee is at Natural Resources, and even that little bit of leverage will disappear if Markey goes to the Senate. The delegation may have reclaimed some Camelot cachet with the arrival of Joseph P. Kennedy III, but his assignment to a pair of B-list panels afford him little opportunity to deliver legislatively.

And, perhaps most remarkably of all, this year there’s no one from the state on the House Appropriations Committee for the first time since the 1930s. Such representation is less important than it was in the age of earmarks, but it can nonetheless prove invaluable when a delegation is trying to put forward a united front in pursuit of a special parochial project or local industry’s cause.

At $9,500, federal spending per person in Massachusetts was a modest 18^th among all the states in fiscal 2011, according to the most recent data available for the new Clout Index. It was 7^th for the two years prior, albeit under a slightly different calculation method.

Fortunately for the people of Boston, minimal tangible damage was done to their city by the exploding of two shrapnel-filled pressure cookers; whatever modest federal aid is needed to put Boylston Street back together or to help the city cover first responders’ overtime can probably be found and dispatched without any need for congressional intervention. If there’s a blip, the Back Bay’s congressman, Michael E. Capuano, is a Democratic leadership ally with enough insider juice to get it smoothed over.

In this respect, this terrorist act is nothing like the last large-scale bombing in an American city. It took longer than a year and all the muscle the very powerful New York delegation could muster to get the city the full measure of federal aid it said it needed after Sept. 11, 2001. That figure was $20 billion — a number the Massachusetts delegation may not be even dare to dream about for years to come.