BBC Washington correspondent Stephen Sackur: There are uneasy times ahead for President Clinton

They will try again on Friday 0930 EST (1430 GMT) to reach an agreement on how the trial should proceed but believe it should be impartial and not split down party lines.

The opening formalities were completed on Thursday with the swearing in of the Chief Justice William Rehnquist as the presiding official and of the senators as the jury.

But the trial then had to be adjourned as efforts to reach an accord failed, with the calling of witnesses remaining the stumbling block.

Republican majority leader Trent Lott said senators should "keep calm and cool and dignified".

His move prompted his Democrat counterpart Tom Daschle to proclaim: "I think there is some common ground."

"We don't want the first vote to be a partisan vote, and it came very close to being one," said Republican Sen. Sam Brownback.

The house prosecutors, or managers, have joined Republican Senators to press for live testimony at the trial.

The parade of witnesses could include the former White House worker, Monica Lewinsky, whose affair with President Clinton led to the impeachment charges of perjury and obstruction of justice.

William Rehnquist (right) was sworn in by 96-year-old Strom Thurmond

Our correspondent says that without witnesses to change the minds of enough Democrats, Republicans believe they have little chance of gaining the two-thirds majority vote needed for conviction in the Senate.

The Democrats, supported by the White House, have resisted and want the whole procedure wrapped up as quickly as possible.

Mr Lott said: "Senator Daschle and I are not dictators. We are leaders that are getting some latitude by our conferences and our caucasus but we have to bring along 98 other Senators."

Washington Correspondent Paul Reynolds has been watching events unfold in the Senate

The Republican plan would allow the House and White House three to five days each to present their cases. If either side wanted to call witnesses, it would then have to explain why and the Senate would vote on each request.

The plan by Senate Democrats would also give each side time to present their cases but would not allow for witnesses.

Mr Lott said they proposed to start the trial next Thursday and end it sometime between 5 February and 12 February.

Our correspondent says that if there is no compromise, the Republicans might enforce their proposal through their majority in the upper chamber.

The White House said opening the trial without clear rules on how to proceed was "manifestly unfair" to President Clinton.

"We may be in a situation where we do move forward without clear rules of the road," White House spokesman Joe Lockhart said.

"I would suggest that that would be a situation, an environment, that is manifestly unfair to the president."