Chart by MB. (Source: Center for Responsive Politics)

When Republican Senators (with two exceptions) decided on a procedural motion Tuesday not to take up a bill that would have removed $2 a billion a year in tax "incentives" for the world's five largest private oil companies, they had one good reason in their pockets. Over the past two decades, since 1989, they have collectively accepted just under $21 million in campaign contributions from oil and gas companies, according to an analysis by the Center for Responsive Politics.

Democrats (with three exceptions), plus the Senate's two independents, voted that there should be a debate about the incentives—a collection of tax breaks that amounts to subsidies of the five oil giants, which in the first quarter of this year made $36 billion in profit. Collectively, the Democrats and independents who voted for a debate have accepted just under $5 million in campaign contributions from oil and gas companies.

Six Republican Senators alone took in twice as much in career oil-company contributions as those 48 Democrats and two independents who voted "Aye" in the Senate. They are: John McCain of Arizona ($2,718,774); Kay Bailey Hutchison ($2,141,025) and John Cornyn ($1,734,950), both of Texas; James "Climate Change Is a Hoax" Inhofe of Oklahoma ($1,256,023), David Vitter of Louisiana ($943,885), and Mitch McConnell of Kentucky ($914,811).

The Democrat who has received the most career campaign contributions is Sen. Mary Landrieu of Louisiana. At $841,388, she ranks No. 7 of Senate incumbents in the oil-contribution sweepstakes. She was one of the three Democrats who joined Republicans in shooting down the motion to have a debate on S. 940, the bill designed to reduce subsidies for the Big Five. The others were Sen. Ben Nelson of Nebraska, who ranks No. 27 at $254,955, and Sen. Mark Begich of Alaska, who has only been in office for two years, and ranks No. 52 at $140,605.

The two Republicans who thought it would be a good idea to actually have a debate on the subsidies are Sen. Susan Collins, ranking No. 48 in career oil-company contributions at $173,293, and Olympia Snowe, ranking No. 53 at $133,754.