The Homeland Security Department (search) will undergo a massive internal review to ensure its policy and funding decisions are being driven by threat assessments, its chief told lawmakers Wednesday.

The department, which opened its doors two years ago this week, has suffered turf battles and growing pains after merging 22 agencies under one roof.

Testifying in his first congressional hearing since being sworn in last month, Homeland Security Secretary Michael Chertoff (search) said changes made after the review will "better enable us to identify, prevent and, if necessary, mitigate and respond to attacks on our homeland."

"We must move away from stovepipe solutions," Chertoff told the House Appropriations subcommittee on Homeland Security. "Instead, we need to look at the entirety of the threat picture when calculating risk and implementing protections."

Chertoff and several of his top lieutenants faced lawmakers across Capitol Hill (search) to lobby for the department's $41.1 billion budget plan for next year — $34.2 billion of which must be approved by Congress. Though funding for a bevy of programs falls short of security levels mandated in new intelligence reforms, the officials insisted the budget blueprint would fulfill the department's needs.

Lawmakers said the department has yet to answer fully how to close gaps in border and transportation security systems or protect critical infrastructure.

"The department's tasks are too important to get bogged down in bureaucratic inertia," said subcommittee chairman Rep. Harold Rogers, R-Ky. "Yet that is exactly what seems to be happening."

At a morning Senate Appropriations hearing, Sen. Patrick Leahy, D-Vt., focused on plans to hire 210 border patrol agents next year — far fewer than the 2,000 required in intelligence reform legislation enacted in December.

"I'm not happy," Leahy told Customs and Border Patrol Commissioner Robert C. Bonner. "Certainly we're not getting anywhere near what Congress mandated."

Bonner said funding for technology — such as radiation monitors and unmanned aerial vehicles — would help make up the staffing difference.

Lawmakers also prodded the department's plans for lifting a hiring freeze at the Immigration and Customs Enforcement bureau, which suffered funding shortfalls last year. ICE Director Michael Garcia said the bureau plans to hire employees next year.