There are 2 scenarios to end Citizens United. Both require only 1 state.
The Move To Amend version of a Constitutional Amendment has been passed in 16 states and could reach 34 in 2 years. https://movetoamend.org/wethepeopleamendment
But rather than wait 2 years, we can shorten the process using the vagueness in Article V of the Constitution. We have two opportunities and should press for both to increase our chances of success.
1. Rescissions not mentioned in Article V
Wikipedia says 33 out of 34 required states have asked for a Convention for a Balanced Budget Amendment (BBA), if you ignore the rescissions. http://en.wikipedia.org/wiki/Balanced_budget_amendment
That is just one state short of asking for a convention. Article V does not mention rescissions. Meanwhile the constitution does NOT limit topics at a convention. So a BBA called convention could discuss Citizens United!
2. Topic limits not mentioned in Article V
Unfortunately some states rescinded the BBA vote leaving 20 states. As mentioned above,16 states have passed bills for an amendment to Overturn Citizens United (OCU). See chart below. When you eliminate overlap, the number of states that voted for a Constitution Convention currently totals 33 out of a required 34. One state short of asking for a convention. Again the constitution does NOT limit topics at a convention.
Obviously we need just one more state as seen in red such as Washington or Minnesota to ask for a Constitutional Convention for either a Balanced Budget Amendment or a Overturn Citizens United amendment. Do you have contacts in Washington or Minnesota to push for having a convention?
Then it is off to the Supreme Court to make the Constitutional Convention a reality.