Election Day has arrived and that means the final installment of the Countdown. For the past two weeks we have chronicled the battle for the House and Senate and now we offer our final ratings of 35 of the most competitive House seats and nine of the most competitive Senate races.

We have made a series of moves in both the Senate and House. Let's start with the Senate, where Democrats need to gain six seats to take control. We have moved two states, both in the direction of Republicans.

We shifted Rhode Island, where Sen. Lincoln Chafee (R) has battled back against former attorney general Sheldon Whitehouse, from Lean Democrat to Tossup.

A month ago this was a race where Democrats had the upper hand. Chafee had won a difficult primary against a conservative opponent, but in a state where President Bush's approval rating is among the lowest in the country, he fell behind Whitehouse. Today the race looks extremely competitive, thanks in part to the Chafee's decision to attack his opponent. Republicans see this as a potential hold, and Democrats acknowledge the race has tightened.

The second change comes in Tennessee, which has moved from Tossup to Lean Republican.

For the last decade this has been a reliably Republican state in federal elections (Democratic Gov. Phil Bredesen, who appears headed toward an easily reelection is an exception), but Rep. Harold Ford Jr. has been skillful in presenting himself as in tune with the state's conservative ideology and values.

Former Chattanooga mayor Bob Corker shook up his campaign -- after pressure from Republican leaders in Washington -- and has been doing better since. He appears now to have a very narrow advantage. Ford needs a huge turnout among African Americans, which is not out of the questions, but he is running uphill in the final day.

In the House, we have made three changes. The first involves Georgia, where we removed Georgia's 8th District from the Countdown list and added the 12th District, which we believe is the more competitive.

The 12th is the seat held by Rep. John Barrow (D); he faces former Rep. Max Burns (R), who left Congress two years ago in an unsuccessful bid for the Senate. We list this race as a Tossup, which makes Marshall the most vulnerable of the two Democrats now on the Countdown list. African American turnout may decide this race.

The second change comes in Washington's 8th District in suburban Seattle, where Rep. Dave Reichert (R) faces Democrat Darcy Burner, an ex-Microsoft manager. This is a Republican district, but the war is not popular in the state and Reichert has put distance between himself and the president. That may save him, and we have shifted this from Tossup to Lean Republican.

The third shift comes in one of the most celebrated districts in the country -- former House Majority Leader Tom DeLay's 22nd District in Texas. We have moved this race from Tossup to Lean Republican.

This is a Republican district, but because of the circumstances of DeLay's resignation from the House, the GOP candidate, Shelley Sekula-Gibbs, will not have her name on the ballot in her bid to defeat former Rep. Nick Lampson. To win, she must count on Republican voters knowing how to write in her name.

For a time Democrats believed that a combination of revulsion over DeLay's ethics charge and the challenges facing any write-in candidate would make it possible for Lampson to overcome the district's conservative tilt. But Republicans appear to be doing a good job educating voters and there are indicators that enough voters are ready to support Sekula-Gibbs to frustrate Democratic hopes of grabbing DeLay's district.

The final changes leave 10 GOP-held seats Leaning Republican and 18 Republican-held seats rated as Tossups. Those ratings underscore the size of the challenge Republicans face in trying to hold the House today.

In the Senate, we have two Republican-held states Leaning Democrat and four others in the Tossup category, with Tennessee the seventh-best opportunity for a pickup. The better Democrats do in House races, the brighter their chances become of taking the Senate as well.

Enjoy the day. Check washingtonpost.com tonight and tomorrow for election results and analysis.

Contested House Races (35)

All 435 U.S. House seats are up for election. Republicans hold 230 seats. Democrats hold 201 seats. One seat is held by an independent who usually caucuses with the Democrats. Four seats -- three Republican and one Democratic -- are vacant. Democrats need a net gain of at least 15 seats to take control of the House with a bare voting majority of 218.

Contested Senate Races (9)

There are 33 Senate races this year, with Democrats defending 18 seats and Republicans defending 15. Republicans currently hold 55 seats and Democrats hold 44. One seat is held by an independent who caucuses with the Democrats. Democrats need a net gain of six seats to take control of the Senate with a bare voting majority of 51. A 50-50 tie would result in an advantage for Republicans because Vice President Cheney would cast tie breaking votes.