IN NOVEMBER, which is only six months away, the United States will have mid-term elections. These will include all the seats in the House of Representatives, one third of the Senate and some governorships of the individual states.

Until recently it was assumed that the Republicans would retain control of both Houses of Congress. The advantage of incumbents, and skilful gerrymandering, mean that only a few seats in Congress normally change hands. Now, however, there is less certainty; the public opinion polls have turned sharply against the Republicans; the President’s ratings are particularly bad.

According to recent polls in The Washington Post, the Democrats are in the lead on all the main issues, including health, education, the economy, taxes, immigration, Iraq, the price of oil and the War on Terror. President Bush’s approval rating has dropped to 33 per cent, with only 32 per cent approval for his handling of Iraq. These figures make it possible that the Democrats will win a majority in the House of Representatives and conceivably in the Senate as well.

In 1973 I was one of the few commentators who expressed much sympathy for President Nixon during the inquiries into Watergate that led to his resignation. I was wrong on the major issue; Nixon was guilty. I was proved right in my concern that Watergate would be a dangerous precedent. Future presidents might suffer the same treatment for partisan reasons, with committee inquiries in both Houses, press investigations, special prosecutors and possibly even impeachment. Presidents are particularly vulnerable in their second terms, when their powers of patronage decline.

Watergate did, indeed, set a precedent for these partisan attacks on a president in his second term. Since Nixon the only presidents to win a second term have been Ronald Reagan, Bill Clinton and George W. Bush. Reagan was attacked on the Iran-Contra issue that became a mini-Watergate. Clinton was impeached. If Mr Bush loses control of the House of Representatives, the Democrats are likely to use their majority to attack him in his last two years in the White House.

Impeachment is not out of the question. Once the precedent of Watergate had been set, the party advantage of such an attack became apparent. The Iran-Contra inquiry in Reagan’s second term was not so damaging as Watergate. The President survived, and the Republican candidate, the elder George Bush, won in 1998. Yet the impeachment of Mr Clinton, his successor, though it failed in the Senate, undoubtedly damaged the Democrats in the 2000 election. Admittedly, Al Gore won in terms of the popular vote. The Supreme Court decision to award the presidency to George W. Bush is hard to reconcile with any earlier interpretation of the Constitution. Yet the impeachment had undermined public confidence in the Democrats. As an election strategy, it worked.

No one can yet tell which candidate the Democrats will choose as their nominee for 2008. Two of them have particularly good reason to remember both Mr Clinton’s impeachment and the Supreme Court’s award of the presidency. They are Mr Gore, the unfortunate candidate, and Hillary Clinton, the wronged wife. The Democrats exploited Watergate ruthlessly; they now have every reason to look back with anger on their own defeat in 2000. I expect they will be equally ruthless in the run-up to 2008.

The obvious target for an impeachment campaign would be the Bush policy in Iraq, an issue on which the Democrats now lead by 50 per cent to 36 in the polls. Iraq has become an unpopular war in the way, if not to the degree, that Vietnam was unpopular.

That will play its part in the mid-term elections themselves, though domestic issues, such as healthcare, may be even more important. There the Democrats lead by 61 per cent to 28.

If the Democrats win a majority in the House of Representatives they are likely to reopen all the questions about the reasons for going to war and about the conduct of it. If the Republicans can hang on to their majority in the Senate, an impeachment is unlikely to succeed. The Clinton impeachment did not succeed in front of the Senate; nevertheless, it helped keep Mr Gore out of the White House, which was its main aim.

Since the outbreak of war in 1939 there have been a number of important friendships between American presidents and British prime ministers. The pattern was set by Roosevelt and Churchill and repeated in various forms by Kennedy and Macmillan, Carter and Callaghan, Reagan and Thatcher, and by the successive friendships of Tony Blair with Clinton and Bush. Mr Blair is the only Prime Minister to have formed two such friendships, and with presidents of different parties.

The Clinton impeachment did not involve Britain or Mr Blair. However, any Democrat attempt to turn the Iraq war into another Watergate would involve British politics. In such inquiries dirt is always found somewhere; in high politics embarrassments always exist. Washington inquiries into Iraq would be much more formidable than the London inquiries of Lord Hutton or Lord Butler.

The US Administration has some timetable for reducing the number of troops in Iraq and Afghanistan. The formation of the new Government in Iraq will be helpful. The British would like to reduce our commitment as well. These plans may be made to fit with the presidential election in 2008 or with a possible British election in 2009. Yet there is no prospect of the war winding down before this November. If the Democrats win the House of Representatives this year they are more likely to win back the presidency in 2008. Their attack on Mr Bush is almost certain to rebound on Mr Blair. Another reason, perhaps, for him to seek early retirement.

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