Senate Democrats are pressing amendments to legislation that would approve the Keystone XL pipeline, arguing their proposals would "actually make it an American jobs bill."
"We have some suggestions on how to make the bill better and actually make it an American jobs bill. If Republicans oppose us they will be making it crystal clear to Americans that they are on the side of narrow special interests rather than on the side of America's middle class," said Sen. Charles Schumer (D-N.Y.), the No. 2 Democrat in the Senate.
"If Republicans vote against these amendments none of them can say it's an American jobs bill," Schumer added.
Markey's measure would ban the export of all oil shipped through the Canada-to-Texas pipeline, while Franken's would require that American steel be used to build the pipeline.
Franken said Sen. Joe Manchin (D-W.Va.), who co-sponsored the Keystone bill with Republicans, has signed on to his amendment.
The senators also said they are expecting Senate Majority Leader Mitch McConnell (R-Ky.) to stand by his word and allow more amendments to the bill.
"This is just the beginning of the amendment process; we have many more that deserve a vote," Schumer said.
Democrats are hoping to get an amendment on the bill that would put Republicans on the record on the science behind climate change.
"We are going to have a chance to find out who climate change deniers in the Senate really are," Schumer said. "Stay tuned."
Supporters of the Keystone bill appear to have the 60 votes that they need to overcome a Democratic filibuster and move the legislation to President Obama's desk.
The White House has said Obama would veto the Keystone bill, however, and Senate Republicans appear to be short of the 67 votes they would need to override him.
Schumer said the amendments being proposed by Democrats Tuesday would "improve" the Keystone bill, "but not enough to vote for it."
— This story was updated at 11:34 a.m.