In a speech on the floor of the Senate Tuesday, Manchin declared his intention to vote against the Democratic version and blasted President Obama for a failure to lead on the budget. 

"Why are we doing all this when the most powerful person in these negotiations — our president  — has failed to lead this debate or offer a serious proposal for spending and cuts that he would be willing to fight for?" Manchin said Tuesday.

Both Manchin and McCaskill are among the Senate Democrats caught in the middle in the spending debate and are under continuous attack from Republicans who sense vulnerability in 2012. Both are top GOP targets.

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The National Republican Senatorial Committee quickly went after McCaskill and eight other Democrats whose seats are up in 2012 for voting against the House GOP plan. 

“If every Missouri family and small business took the same approach to spending and debt that Claire McCaskillClaire Conner McCaskillMissouri county issues travel advisory for Lake of the Ozarks after Memorial Day parties Senate faces protracted floor fight over judges amid pandemic safety concerns Amash on eyeing presidential bid: 'Millions of Americans' want someone other than Trump, Biden MORE takes with spending their tax dollars, every single one of them would be bankrupt and destitute," NRSC spokesman Chris Bond said after Wednesday's vote.

Another Republican target in 2012 -- Sen. Jon TesterJonathan (Jon) TesterThe 10 Senate seats most likely to flip Memorial Day during COVID-19: How to aid our country's veterans Senate votes to reauthorize intel programs with added legal protections MORE (Mont.) voted in favor of the Senate Democratic plan to cut $4.7 billion Wednesday.

Three Senate Republicans also voted against the House plan Wednesday, arguing the cuts aren't deep enough. Sens. Rand PaulRandal (Rand) Howard PaulTrump urges GOP to vote against bill reauthorizing surveillance powers Sunday shows preview: States begin to reopen even as some areas in US see case counts increase Congress headed toward unemployment showdown MORE (Ky.), Mike LeeMichael (Mike) Shumway LeeThis week: Surveillance fight sets early test for House's proxy voting White House withdraws ATF nominee after GOP pushback Hillicon Valley: Commerce announces new Huawei restrictions | Russian meddling report round five | Google's ad business in spotlight MORE (Utah) and Jim DeMint (S.C.) all voted "no." 

Along with the five Democrats up for reelection next year, another six Senators who caucus with Democrats voted against the Democratic measure Wednesday. Sens. Kay Hagen (N.C.), Bernie SandersBernie SandersBiden will help close out Texas Democrats' virtual convention: report Senate Dems press DOJ over coronavirus safety precautions in juvenile detention centers Gabbard drops defamation lawsuit against Clinton MORE (Vt.), Jim Webb (Va.), Michael BennetMichael Farrand BennetSenate Democrat introduces bill to protect food supply Congress headed toward unemployment showdown Fight emerges over unemployment benefits in next relief bill MORE (Colo.), Carl LevinCarl Milton LevinSenator Tom Coburn's government oversight legacy The Trumpification of the federal courts Global health is the last bastion of bipartisan foreign policy MORE (Mich.) and Mark UdallMark Emery UdallThe 10 Senate seats most likely to flip Democratic presidential race comes into sharp focus Democrats will win back the Senate majority in 2020, all thanks to President Trump MORE (Colo.) also voted "no." 

-Updated at 4:32 p.m.