Mitt Romney may have all but locked up the Republican nomination with his victories in the East Coast primaries this week, but Ron Paul and his army of acolytes aren't ready to give up the fight just yet.

As the rest of the political world's attention shifts to the general election, Paul is still quietly amassing delegates at district and county conventions, and is now poised to take a real bite — or at least a big nibble — out of Romney's delegate total.

In just the last week, Paul locked up 49 delegates, including five in Pennsylvania and four in Rhode Island, two states thought to be firmly on Romney's turf. In Minnesota, Paul won 20 of the 24 delegates awarded at last weekend's district caucuses, an impressive sweep that guarantees that Paul will control a majority of the state's delegation at the Republican National Convention.

And despite staunch opposition from the state Republican Party, Paul took 20 of the 40 delegates awarded in Missouri last weekend, according to campaign chairman Jesse Benton.

In at least five other states — Colorado, Nevada, Iowa, Washington, and Maine — Paul has done remarkably well at county and district conventions, and his supporters are expected to win a big chunk of the RNC delegates at the state conventions later this spring.

"We are very pleased with the results," Benton told Business Insider. "We still have a long way to go, but we've done very, very well at the county caucuses and district conventions and that bodes well for our strength when we get to the state conventions. Now we need to keep our nose to the grindstone."

Even Rick Santorum, who earlier in the race accused Paul of shilling for Romney, acknowledged the Texas Congressman's impressive organization this week, telling CNN's Piers Morgan that "Ron Paul is working the delegates hard."

In a surprising twist, a lot of Paul's recent success can actually be attributed to Santorum's decision to suspend his campaign earlier this month. In many places, Santorum supporters have banded together with Paul organizers in an attempt to deny Romney delegates.

In Colorado, for example, Santorum supporters have bonded with their Paul counterparts over a shared skepticism of Romney's conservative values. Although the Colorado GOP won't select its RNC delegates until the state convention next month, Paul organizers have gotten many of Santorum's pledged delegates to commit to supporting Paul over Romney.

"In Colorado, there is a real anti-Establishment sense — they want to send a very conservative delegation to the national convention," Benton told BI. "We're fighting it out, and we think there are enough Santorum delegates that are sympathetic to Ron Paul who will come over to us."

In Washington, Santorum's county caucus organizer sent an open letter to his fellow supporters urging them to vote for Paul's delegates rather than Romney's.

Here's an excerpt of the letter, obtained by Business Insider:

Romney wants everybody to quit. Quitting may be his solution when his back is up to the wall, but it's not what we want from our leaders. Our country has it's back up against the wall! We need principled fighters and not a pretty boy in a suit. We nominate Romney and it's the equivalent of making him the starting quarterback because he simply looks good in the uniform. He's a defensive coordinators dream. The mere fact he wins in the same places liberals do in the general election says a lot.

At some point, and it might as well be now, people are going to reign back power from party leaders, unite and actually make something like a Paul/Santorum unity slate work. As I see it, it's the only way to balance power, restore it back to the people and take it away from big money.

Those against such an alliance, especially elected state delegates, might want to address future problems and complaints concerning government to the person in the mirror. I fail to see the logic in people not trusting such an arrangement that both Paul and Santorum's people have agreed to, yet they'll trust the same people running the party for years that have helped bring us to this junction in history.

That Santorum's supporters are taking a second look at Ron Paul rather than vote for Romney's delegates is an indication that the former Massachusetts governor still has major problems with his party's Republican base.

"The plurality of them just don't want to vote for Romney," Doug Wead, a senior advisor to the Paul campaign, told Business Insider. “A lot of people are upset that Romney has not reached out to them at all. [They feel like] 'Why in the hell should we support him when he’s not asking for our support or doing a single thing to get it."

Both Wead and Benton concede that it would be difficult — if not impossible — to deny Romney the delegate majority he needs to win the nomination. The goal now, Benton told BI, is "to win as many delegates as we possibly can."

"We want to have a strong, respectful presence that says 'We are here, we are are going to participate, and we are ready to talk about the party platform with you if you take our issues seriously," he said. "We're going to send a message that the liberty wing of the Republican party is strong, and that it isn't going anywhere."

The Romney campaign declined to comment on Paul's delegate wins. But if Paul continues his hot streak, the presumptive nominees might not be able to ignore the libertarian iconoclast and his army of delegates by the time the national convention rolls around.