If Rep. John Conyers Jr. can’t win re-election after he was ruled ineligible for the Democratic primary ballot Tuesday, it could set up a fight for the ranking member slot on the Judiciary Committee, with House Democrats already divided in an increasingly ugly showdown between two colleagues vying for their party’s top slot on the Energy and Commerce Committee.  

The re-election of Conyers has been thrown into doubt  after the 25-term Michigan Democrat failed to collect valid signatures to qualify for the Democratic primary ballot.  

Conyers could seek to keep his seat by challenging the ruling, launching a write-in campaign or running as an independent, but if none of those contingency plans pan out, it will leave an opening several of his colleagues could be eager to fill. Like the race between New Jersey’s  Frank Pallone Jr. and California’s Anna G. Eshoo to succeed retiring Energy and Commerce ranking member Henry A. Waxman, D-Calif., the race to succeed Conyers could come down to a more senior male member from the East Coast and an only-slightly-less senior woman from the West Coast.  

Democrats defer to seniority in most cases when it comes to making plum committee leadership assignments, which would make the heir apparent the panel’s current No. 2 Democrat, Jerrold Nadler of New York, who has been in Congress 11 terms.  

Except the No. 4 Democrat is Zoe Lofgren of California, who is in her 10th term in office. Like Eshoo, Lofgren could decide she is just as qualified to be the top Democrat on the committee as the man who proceeds her, forcing peers to decide how closely they subscribe to certain unwritten but deeply-held principles that govern the caucus.  

As with the Pallone and Eshoo face-off, Democrats who put seniority first in cases where the two candidates are otherwise qualified and well-respected will side with Nadler. The Congressional Black Caucus in particular has been a fierce defender of the seniority system in order to protect their members against slights when they are in line for promotions.  

The No. 3 Democrat on the Judiciary Committee is CBC member Robert C. Scott of Virginia, but he is the current No. 2 on the Committee on Education and the Workforce , and he has said he will seek the ranking slot being left open by the retirement of George Miller of California.  

Minority Leader Nancy Pelosi, D-Calif., meanwhile, will be faced with a choice as to whether she weighs in publicly, should Conyers be out of a job and Nadler and Lofgren decide to go head-to-head. Pelosi stunned colleagues earlier this year when she publicly endorsed Eshoo, a fellow Californian and close friend, over Pallone, and there could be precedent now for Pelosi to make another move in support of another California woman.  

But a lot has to happen before all that: The Michigan Democratic primary doesn’t occur until Aug. 5, giving Conyers some time to chart out his next move, and the Democratic Congressional Campaign Committee hasn’t abandoned him yet.  

“The DCCC fully supports Representative Conyers in his re-election campaign, and I have every confidence that when this long process is complete, Representative Conyers will continue to serve the people of Michigan in Congress,” DCCC chairman Steve Israel, D-N.Y., said in a statement Tuesday night. “As the next Dean of the House, the Michigan delegation and pillar of the Democratic party, Representative Conyers will remain one of the most respected voices in Congress.”  

Democrats won’t vote for committee ranking member assignments for the 114th Congress until after the midterm elections.