If the bill dies, Republicans will have suceeded in bringing the issue to the forefront and killing it on the "high ground" of free speech.
But arguments against the constitionality of such a ban are unfounded, according to Marvin Kalb, director of Harvard's Shorenstein Center on the Press, Politics and Public Policy. The provision wouldn't stop people from contributing to political parties or campaings, he said.
"[The ban] limits the flow of soft money into the system," he said.
McCain said many politicians are "scared to death" about the ban on soft money because it would force them to raise money in smaller increments and from more donors.
"Both Democrats and Republicans have obstructed [the bill] for reasons each party may feel is fully justified," Kalb said.
"These arguments are made by people who do not want to reform the campaign finance system," he said.
Of course, if enough Republicans can be swayed to pass the bill and it eventually becomes law, that is no guarantee that the system will be reformed.
The bill is both explicit and vague; that is, it calls for a ban on soft money and leaves the rest to judicial interpretation. And whether or not money is removed as the "dominant force," from campaigns, as the bill's co-sponsor Russ Feingold (D-Wis.) enthusiastically wrote in 1995, will remain to be seen.
McCain has raised many contemptuous eyebrows within the Republican party by his vociferous support for finance reform and his drafting of the legislation. But the war hero is extremely popular within his home state of Arizona, notes Kalb, and Republicans would never isolate him from the core of their party.
Still, by aligning with a mostly Democratic coalition to reform the system, he demonstrates the independence that allows him to buck the Republican system on issues like "English-Only laws" (which he opposes).
But McCain's forthright style endears him to most of his collegues, including Kerry, who credits the senator's boldness in leading the campaign reform fight.
McCain made it clear last night he won't give up the fight for meaningful campaign reform if SR25 fails by vote or by legislative procedure today.
"Senator Feingold and I will keep pressing our case even if we fail tomorrow. We will offer a ban on soft money to whatever legislation is next considered by the Senate," he said.