A Senate panel investigation into the use of intelligence leading up the the Iraq war remains in limbo after almost three years of politically charged clashes over the content and conclusions of the inquiry.

Nonetheless, Pat Roberts, R-Kan., chairman of the Senate Intelligence Committee, set still more deadlines Tuesday for finalizing some of the work despite those differences.

With midterm elections looming, the investigation is mired in fundamental issues, such as lawmakers’ squabbling over the scope of the investigation and whether it should draw conclusions. It is also slowed by intelligence community resistance and a pending Pentagon inspector general investigation, lawmakers said.

Even under the new deadlines, the investigation would have virtually no chance of being completed before the fall elections.

The first phase of the investigation culminated in a report approved by the panel in July 2004 that primarily targeted the CIA for its failings. Roberts agreed in February 2004 to conduct a second phase of the investigation that addresses whether the Bush administration misused intelligence. Roberts then decided this spring to break up the “Phase II” investigation into five parts.

With several of his previously set deadlines for the second phase of the investigation already lapsed, Roberts said Tuesday his committee would hold a business meeting July 13 to determine the process for finalizing two reports before the August break and the third in September.

The first two reports would address postwar findings on Saddam Hussein’s connections to terrorism and weapons of mass destruction capabilities, and how the intelligence community used information provided by the Iraqi National Congress, an exile organization headed by Ahmed Chalabi. The third report would address prewar intelligence assessments of postwar Iraq.

Another segment of the Phase II investigation is being held up by a pending Pentagon inspector general report on activities conducted by the Pentagon’s Office of Special Plans under former Undersecretary of Defense Douglas J. Feith. Roberts said he wants to await the completion of that report before pursuing his own inquiry further.

The final segment, which is the most controversial, would address the administration’s public statements on Iraq. However, Roberts and panel Democrats have fought over Roberts’ desire to include the prewar remarks of other government officials, including Democratic senators.

Roberts said Democrats are guilty of “moving goal posts syndrome” and have continually pressed to expand the investigation.

That is not the only point of dispute, however. Ranking Democrat John D. Rockefeller IV of West Virginia said the panel is logjammed on whether the reports should contain not only statements of fact but also conclusions. “[Roberts] doesn’t want any,” Rockefeller said.

Rockefeller characterized the negotiations on the investigation as “hot and heavy,” but said he wanted to make sure the reports included conclusions.

“Only conclusions can point the way to policy,” he said.

In other committee investigations, Rockefeller said, the panel has been able to arrive at conclusions even when Democrats sometimes offered additional views.

Roberts and Rockefeller agree, on the other hand, that Director of National Intelligence John D. Negroponte has put up hurdles by releasing documents to the committee that are loaded with “black marks” — and that receiving declassified information has been difficult.

The investigation has been marked by partisan feuding and slipped deadlines.

Democrats shined a spotlight on the issue last Nov. 1, when Minority Leader Harry Reid, D-Nev., forced the Senate into closed session to discuss the long-delayed intelligence probe, accusing Republicans of trying to forestall any serious inquiry.

Furious Republicans called the maneuver a “political stunt.” But Roberts agreed to step up efforts to complete the investigation, while vehemently denying accusations that Republicans were at fault for its delay.

In March, Roberts said he expected the committee to start drawing up conclusions from the investigation at the beginning of April. As that deadline neared, Roberts postponed it until after the April recess. In an interview at the time, he again insisted that committee staff were working hard to get the probe done in the spring.