WASHINGTON — U.S. Sen. Susan Collins said her biggest concern over a recent report card that assesses successes and shortfalls of the federal 9-11 Commission is the nation’s failure to take seriously the problem of homegrown terrorism.

As the ranking Republican on the Homeland Security and Governmental Affairs Committee, Collins closely analyzed the 10th anniversary report card submitted by the Bipartisan Policy Center.

“The Homeland Security Committee first sounded the alarm about homegrown terrorism five years ago, during my chairmanship, and has held more than a dozen hearings on the topic,” Collins said in a statement Wednesday. “As the result of our investigations, we learned that some individuals within the United States, in both our prison system and our communities, are being inspired by al-Qaida’s violent Islamist extremism to plan and execute attacks, often acting as ‘lone wolves’ without direct orders from abroad.”

Although the report card lists successes in the 10 years since the worst terrorist attacks in the nation’s history — including improved airline passenger screening and better information-sharing across agencies — it also highlights recommendations that have yet to be implemented.

Among those are: ensuring that a unified command is adopted for incidents involving multiple agencies or jurisdictions; increased assignment of radio spectrum for public safety purposes; and creating a single, principal point of oversight and review for homeland security.

In Maine, Robert McAleer, director of the Maine Emergency Management Agency, said his organization has received and invested more than $128 million in federal Homeland Security grants since 2002. Among other things, he said, the money has been used to protect critical communications infrastructure, to build and improve emergency operations centers across the state, and to provide training for emergency response teams.

In addition, McAleer said, federal dollars have enabled the purchase of equipment, including four state-of-the-art mobile command units, generators for emergency power supplies, and Bangor’s ill-fated hovercraft which suffered a damaged propellor shortly after its purchase and has been unusable ever since.

MEMA also has invested in a large number of emergency communications radios.

“We’ve bought an awful lot of radios,” McAleer said. That’s because any radio made before 1998 won’t be usable after January 2013 when emergency responders will be assigned to a new, narrow-band frequency, he said, and also to ensure that all the radios in the state are able to “talk” to each other.

As a result of the investment in radio units and other equipment, McAleer said Maine’s communications interoperability is in pretty good shape. Maine also has made good progress in implementing incident command protocols in large-scale emergencies, ensuring a coordinated and more effective response, he said. And MEMA has invested in a secure system for credentialling emergency workers, minimizing the likelihood of infiltration of the emergency response team by terrorists.

“I think we’re in pretty good shape,” he said.

But at the national level, Collins lodged her concerns.

“I am troubled that the White House has not named a lead federal agency to coordinate disparate efforts to combat homegrown terrorism,” said Collins. “I urge the [Obama] administration to establish a unified front against this important and evolving threat.”

In the last two years, the number of homegrown terrorist plots has escalated sharply. The Congressional Research Service has reported that between May 2009 and July 2011, arrests were made in connection with 31 “homegrown” plots by American citizens or legal permanent residents of the United States. By comparison, in the more than seven years from Sept. 11, 2001, through May 2009, there were only 21 such plots.

The Bipartisan Policy Center is chaired by former U.S. Rep. Lee Hamilton, a Democrat from Indiana, and former New Jersey Gov. Tom Kean, a Republican.

The center’s 9-11 report card concludes that the United States is undoubtedly safer than it was a decade ago but urges a continual reassessment of priorities and expenditures going forward.

“One of our major deficiencies before the 9-11 attacks was a failure by national security agencies to adapt quickly to new and different kinds of enemies,” the report stated. “We must not make that mistake again.”