The following Congressional sessions that were analyzed mark crucial turning points in the distribution of partisan seats (and hence partisan power) between Republicans and Democrats.  The 103rd Congress, for example, marks the last Congressional session where the Democrats had a clear majority in the Senate. The 109th Congress is the current session, with the Republicans holding a solid majority of seats. The 107th Congress represented a 50-50 Senate between the parties.

For each of these Congressional sessions, we compared the number of votes each party's electedSenators  received to see which party's sitting Senators actually won the support of more voters. In addition, we analyzed how closely a party's percentage of the votes cast for winning candidates matched its actual percentage of seats (termed a "seat to vote distortion" here).

Note that the United States Senate consists of 100 elected Senators, 2 from each state, where each Senator is elected for a 6-year term.  Senate elections are held every two years, where 34 seats are up for re-election every two years.  Thus, the representation accorded to Senators in a particular Congressional session, such as the 109th, would constitute the votes from the past three Senate elections: 2000, 2002, and 2004. 

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The 103rd Congress was analyzed because it marked the last session of Congress when the Democrats retained a Senate majority. The Democrats had previously maintained this power for quite a long time up to the 103rd Congress, until the following 1994 Senate elections, when the Democrats lost their Senate majority to the Republicans.

The Democrats controlled a Senate majority by securing 56 Senate seats, while the Republicans faced a Senate minority, with only 44 Senate Seats.  It is crucial to note, however, that the 56 seats for the Democrats represented a staggering 64 million votes cast for those Senators, while the 44 seats for the Republicans represented a paltry 33 million votes cast for those Senators.

Democratic Senators' Voters	63,811,051	# of Democratic Senators	56
Republican Senators' Voters	33,419,329	# of Republican Senators	44

Seat to Vote Distortion: Given the number of votes received by the Democratic and Republican Senators, under a system of proportional representation, the Democrats should have taken 66 seats, while the Republicans should have taken 33 seats.  Thus the Democrats were under-represented by 10%, and the Republicans were over-represented by 11%.

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The 107th Congress was analyzed because this was the session when the Democrats and Republicans, prior to a shift of power, evenly split Senate seats between the two parties.  As it began, it was a reported 50/50 even split between Democrats and Republicans in the Senate, with the newly elected Vice President Dick Cheney, as President of the Senate, with the constitutional right to cast a tie-breaking vote.  However, the shift of power changed when Vermont’s Independent Senator, Jim Jeffords, previously Republican, shifted his support to caucusing with the Democrats. 

Prior to the shift of power, however, it was noted that opening up the 107th session, the Democrats controlled 50 Senate seats, and the Republicans as well controlled 50 Senate seats. However, it is crucial to note that the 50 seats for the Democrats represented a staggering 59 million votes cast for those Senators, while the 50 seats for the Republicans represented only 43 million votes cast for those Senators.

Democratic Senators' Voters	59,070,316	# of Democratic Senators	50
Republican Senators' Voters	43,302,935	# of Republican Senators	50

Seat to Vote Distortion: Given the number of votes received by the Democratic and Republican Senators, under a system of proportional representation, the Democrats should have taken 58 seats, while the Republicans should have taken 42 seats.  Thus the Democrats were under-represented by 8%, and the Republicans were over-represented by 8%.

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The 109th Congress was analyzed because it is the current Congressional session, and it marks a well-defined Republican majority in the Senate, complemented by both a Republican majority in the House, as well as a Republican President.

The current session of the Senate marks a clear Republican majority, with the Republicans controlling a commanding 55 seats, and the Democrats facing a Senate minority of 45 seats (including Jefford’s Independent seat).  NOTE: For purposes of this report, however, we counted Jeffords' votes for the Republican Party, given that this report is intended to measure which party represents America based on the behavior of voters. Senators Jeffords is counted as a Republican since the voters that last put him in office did so with him running on the Republican label in 2000. Hence, our report counts him as such, giving the Republicans 56 seats and the Democrats 44 seats. Once again, however, the representation is still incredibly skewed, as the 56 seats for the Republicans were obtained with the votes of only 58 million people who supported those Senators , while the 44 seats obtained for the Democrats represent the support of a much greater 61 million people who supported the minority Senators.

Democratic Senators' Voters	61,249,001	# of Democratic Senators	44
Republican Senators' Voters	58,407,690	# of Republican Senators	56

Seat to Vote Distortion: Given the number of votes the Democratic Senators received, compared with the number of votes the Republican Senators received, under a system of proportional representation, the Democrats should have taken 51 seats, while the Republicans should have taken 49 seats.  Thus the Democrats were under-represented by 7%, and the Republicans were over-represented by 7%.

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Which Party Received More Votes?- For the 109th Congress, we also combined the votes of all Democratic Senate candidates (wheter they won or lost) and then combined the votes of all the Republican candidates (wheter they won or lost) to see which party as a whole received more votes. Note that the comparison below looks at how many votes each parties' candidates received, regardless of whether they won or not. Notably, the Democratic Senate candidates, though currently the minority party, received over 2 million more votes than all of the Republican candidates combined. This was the case even when counting the votes of Senator Jeffords as Republican votes (Senator Jeffords ran in 2000 as a Republican but now caucuses with the Democrats).

Votes for Democratic Senate Candidates	Votes for Republican Senate Candidates
99,088,108	97,069,157

*Note that these figures exclude the 2000 Senate races in Georgia (Zell Miller vs. Mack Mattingly) and Missouri (Jean Carnahan vs. John Aschcroft), because those seats were both up for election twice within the period studied. Hence, we used the most recent election results to calculate the partisan votes for those seats, so that every Senate race in the 109th Congress only had one set of election results. Though this would potentially reduce the margin for the measure of Democratic votes, given that the Democratic candidates won in the earlier elections but lost in the more recent ones, the Democrats nevertheless still received more aggregate votes than the Republican Party. Additionally, the Lousiana Senate races included here aggregate all of the Democratic and Republican Senate candidates in the November elections.