For most Democrats on Capitol Hill, mention of Senators Manchin or Sinema conjures a single, jarring image— a human roadblock. And that’s no exaggeration. The two Democratic senators,—representing West Virginia and Arizona, respectively—have come under fire recently as a result of accusations that they are blocking their party’s agenda. Initially, the senators were castigated for their refusal to support a measure to abolish the filibuster in the Senate, which was widely supported by other members of their party. Now, they’re in the spotlight once again for blocking the passage of a $3.5 trillion budget reconciliation infrastructure package, a budget bill stylized to be representative of the Democrats’ vision for the nation amidst a pandemic as well as a stepping stone to retaining Democratic majorities after the 2022 midterm elections. 

The fight over the filibuster began earlier this year when Democrats attempted to pass a landmark election reform bill— known as S1— for which they did not expect to garner bipartisan support. The abolishment of the filibuster would drop a 60-vote requirement to a simple majority of 51 votes, allowing Democrats to employ their Senate majority to pass many more legislations. The filibuster’s high vote requirement has already proved troublesome for Democrats, with Republicans using it to block a motion to create a commission to investigate the Jan. 6 Capitol riots. Senator Joe Manchin spoke out against the abolishment almost immediately, stating that “I will not vote to eliminate or weaken the filibuster.” Senator Sinema soon followed suit, explaining that “we have more to lose than gain by abolishing the filibuster.” The two senators are also provided a significant amount of cover when the filibuster is left in place. In all likelihood, the filibuster prevents tough votes on issues like abortion from ever reaching a final vote, and that allows these moderate senators to avoid taking stances that might alienate parts of their constituency.

Without the backing of senators Manchin and Sinema, the Democrats do not have the necessary votes to successfully abolish the filibuster and pursue regular routes to pass components of their agenda. They turned instead to a process known as budget reconciliation— a type of legislative process that would evade the filibuster and require only a simple majority in both chambers to pass, but is much more limited in scope. Instances where this process would be applied include changes to the debt ceiling, revenue intake, or spending limits. From that strategy sprouted the $3.5 trillion Democratic budget reconciliation package that includes a slew of legislative priorities from Biden’s outlined agenda. Not only are these two senators blocking the filibuster and forcing their party to pursue the more arduous task of  budget reconciliation, they’re not blocking the budget reconciliation itself and haggling its topline price.

So, what influences are behind Senators Manchin and Sinema’s obstruction of the Democratic agenda?

Primarily, many critics point to the constituencies that the senators represent. Senator Manchin represents the state of West Virginia, where both chambers of the state legislature are under Republican control and a Democratic majority exceedingly rare. To run successfully, he is compelled to cater to the interests of a largely Republican-leaning constituency. Manchin’s emphasis on fiscal conservatism is one of the phenomena best explained by his constituency. Time and time again, Manchin has attempted to haggle down the $3.5 trillion price tag of this budget reconciliation package. He is now demanding that the price be curtailed all the way down to $1.5 trillion. Senator Sinema finds herself in a similarly problematic political position. Sinema narrowly won the seat that was previously held by Senator Jeff Flake until he decided to not run for reelection. Given her narrow initial victory, she faces a sticky challenge for reelection. Clearly, their political vulnerability is one key to understanding their staunch political opposition to supporting the filibuster or budget reconciliation package.

Senator Manchin also represents the largely coal-dependent state of West Virginia. A majority of his constituency relies on the fossil-fuel industry for access to jobs, but that same, in turn, damages the health of his constituents and the well-being of the state’s natural environments.  Manchin has often attributed his obstruction of clean energy policies to the composition of his constituency— and this case is no different. The budget reconciliation already contains a myriad of progressive energy policies, which, as chairman of the Energy committee, Manchin has already made efforts to strike down. He has enumerated numerous times that the climate proposal within the bill “makes no sense at all.” He cites this conflict as a contributing factor to his opposition of the bill, posturing that “It’s not going to be at $3.5 [trillion], I can assure you.”

But that doesn’t tell the whole story. For Senator Manchin, accusations of being subject to outside influences are no new struggle. Many critics argue that Manchin isn’t just fighting clean energy proposals in the budget reconciliation because of his coal-dependent state, but because of his ties to nefarious outside influences. Prominent among these is famed fossil-fuel company Exxon Mobil. In a recently leaked video, Keith McCoy, senior director for federal relations for Exxon, is seen revealing the company’s lobbying practices frankly. “Joe Manchin, I talk to his office every week,” McCoy boasts to the interviewer in the video. He goes on to identify Manchin as the company’s “kingmaker” in Congress, allowing them to push their pro-fossil fuel agenda among Democrats. With voices like this in his ear, it’s no surprise that Manchin would so vehemently oppose a budget reconciliation bill intended to usher in a new era of clean energy and environmental justice policy.

On the other hand, the story of Senator Sinema’s opposition is quite different. Many critics still struggle to understand her staunch obstruction, pointing to her experience working in a Republican Arizona state legislature as an influence on her belief in bipartisanship. Publishing a Washington Post op-ed denouncing calls for abolishing the filibuster—and touting bipartisanship—Sinema has doubled down on her position. She has also latched onto calls from Manchin and other moderate Democrats in the House of Representatives to lower the ambitiousness and price tag of the budget reconciliation package. 

All in all, senators Manchin and Sinema, or as some like to refer to them, “Manchema,” are growing into their roles as the thorns upon Biden’s agenda for the Democratic Party. Without their support for either the filibuster or the budget reconciliation , these measures become extremely vulnerable. President Biden’s frustration with this divide is clear— he recently met with both wings of the party to reach an agreement on the passage of the budget reconciliation. Whether “Manchema” tanks this package is yet to be seen, but for now, they present a substantial roadblock.