The Big Question: Will the new Democratic Congress transform politics in Washington?

Why we are asking the question now?

The new Democratic-controlled 110th Congress, chosen at last November's midterm elections, convened yesterday. The party has a majority in the House of Representatives and the Senate for the first time since January 1995 (with the exception of an 18-month period until January 2003 when a sitting Republican crossed the aisle). Otherwise they have not had a sniff of real power in Washington since George W Bush entered the White House. All that now changes. Mr Bush is still President, but he faces the novel experience of a hostile legislature, which will send him laws he opposes and conduct the sort of tough investigatory hearings - on domestic issues as well as Iraq - that he was spared during his first six years when the President's own party ran Congress.

How big a blow is it for the White House?

A huge one, that Mr Bush and his top strategist Karl Rove certainly weren't expecting. After a series of high-profile scandals, and a general feeling they had been around too long, Republicans were braced for losing the House. But loss of a 10-seat majority in the 100-seat Senate was a shock. The only consolation is they might conceivably regain that majority back in the months ahead, depending on the health of South Dakota Democrat Tim Johnson, who suffered a severe brain illness in December. His condition is still listed as critical. If he dies or is forced to resign, a replacement would be named by the state's Republican governor, who would presumably appoint a Republican. That would create a 50-50 split with Vice President Dick Cheney holding the tie breaking vote. But the Democrats will do anything to avoid this. Expect an "El Cid strategy" where even lifeless, the political warrior is strapped into the saddle and sent into battle.

What exactly are the Democrats planning?

Nancy Pelosi, the incoming Speaker (and the first woman to hold the third-ranking post under the US constitution) has mapped out an agenda of largely populist measures the House will pass during an initial "100 Hours" legislative blitz. This will start with new ethics rules governing lawmakers' ties with lobbyists, followed by the first increase in the minimum wage since 1997, bills expanding embryonic stem cell research, moves to lower drug prices and cut tax breaks for energy companies, and allow the government to negotiate lower prescription drug prices. The Democrats also want to restore 'pay-as-you-go' rules for federal spending, whereby any tax cut or spending increase would be offset by other tax increases or spending cuts. They also say they will pass a bill implementing unfulfilled recommendations of the 9/11 Commission, thus bolstering the party's national security credentials. All this is supposed to happen over the first 100 hours of floor session, in practice over the next fortnight, and before Mr Bush delivers his State of the Union address on 23 January.

Exactly what will they be able to do?

Certainly not everything they want. The minimum wage proposal already has Mr Bush's grudging support, while the new ethics rules, banning gifts and meals aid by lobbyists, will certainly go through. The rest is more problematic. Mr Bush used his only veto thus far to block an earlier bill passed by the Republican-controlled Congress on stem cell research. Even though the President has never been as weak, there is no reason to suppose he won't veto a repeat measure. The 9/11 Commission pledge looks good on paper; in practice turf battles on Capitol Hill will prevent the streamlining of Congressional oversight of intelligence that was a key recommendation of the 2004 report.

There are two other obstacles in Ms Pelosi's way. One is the Presidential veto. In both House and Senate, the Democrats are far short of the two-thirds majority required to override. The other is the hybrid nature of Congress. Strict procedural rules in the House mean the majority party can ram through almost anything it likes. Senate rules, however, offer endless opportunities for delay by the minority, above all the filibuster which only a 60-vote "super-majority" can break.

Even with a fit Mr Johnson, the Democrats only have 51 votes. On top of that, there is a conservative-liberal split in Democratic ranks on key social issues like gay rights and abortion. Thus, important legislation is likely to pass only on a bipartisan basis. For all the fine promises to co-operate, expect normal partisan politics to resume shortly - especially with a Presidential election on the horizon.

So is there any chance of improving the tarnished image of Congress?

Frankly, not much. Americans were disgusted with the outgoing 'do-nothing' Republican-run 109th Congress, which in its final year sat for just 102 days. By the end, its approval rating of only 25 per cent made even George W Bush look like a rock star. The ethics rule changes are the bare minimum required, after the Jack Abramoff and Randy 'Duke' Cunningham scandals, which saw two Republican Congressmen convicted of bribe-taking and influence-peddling. But "draining the swamp," as Ms Pelosi promises, requires draining a Democratic swamp as well.

Republican lobbyists have lost the clout they gained under the former (now disgraced) House majority leader Tom "the Hammer" DeLay. But their Democratic counterparts are emerging into the sunshine, fully expecting their piece of the action. The fact is that money is so vital for US politics that the role of the lobbyists, in terms of fundraising, is irreplaceable.

And for their pious talk, this is payback time for Democrats - in the House especially - after 12 years of being steamrollered by Republicans. Expect collision and stalemate, and renewed public grumbling about "those politicians in Washington".

But what about Iraq?

This could produce the most momentous clash of all. Mr Bush and the executive branch he heads still decide Iraq policy. But his expected proposal next week for a 20,000-plus troop "surge" in Iraq is regarded with deep scepticism not only by Democrats but also by many Republicans on Capitol Hill. Iraq could trigger the real nightmare for a highly unpopular "lame duck" President - that moderate Republicans, looking to their own survival in 2008, could make common cause with Democrats.

Even so, however many klieg-light hearings the Democrats convene to scrutinise Iraq policy, they will not use either of the truly drastic options theoretically open to them - an initiation of impeachment proceedings against Mr Bush for his mendacious handling of pre-war intelligence or a cut-off of funding for the war that would instantly bring the troops home. The first is "off the table" Ms Pelosi has said. The second, given the sacrosanct status of the military, is unthinkable.

Can the Democrats make a real difference?

Yes...

* America is yearning for change, and the opportunity is there for the Democrats if they wish to grasp it

* Mr Bush is so weak politically that he will not be able to block everything the Democrats seek to accomplish

* The Democrats need results to bolster their chances of recapturing the White House and retaining Congress in 2008

No...

* Blunders already made by the new Speaker of the House, Nancy Pelosi, show she will be unable to control her troops

* The party's wafer-thin majority in the Senate gives Republicans a blocking minority on anything of importance

* Although the Democrats abhor Mr Bush's Iraq policy, they have no agreed alternative to replace it with