*Editor's note: This story has been updated throughout.

The main super PACs supporting Ted Cruz on Sunday reported raising $1.2 million in the second half of 2015, a fraction of the sum they took in 10 months ago when they shocked the political world with an eight-figure debut. 

Yet the groups, organized under an umbrella known as Keep the Promise, still have nearly $30 million in the bank, an enviable war chest on the eve of the first nominating contest. And they are being joined by another pro-Cruz super PAC that is showing it can also move around millions of dollars in support of the U.S. senator from Texas. 

Those and other details about the groups' finances were due to the Federal Election Commission on Sunday, a day before Iowa's its first-in-the-nation caucuses. Among the top-raising super PACs supporting a Republican candidate were those backing former Florida Gov. Jeb Bush and U.S. Sen. Marco Rubio of Florida, which took in $14.4 million and $15.1 million, respectively. 

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The $1.2 million haul by the four pro-Cruz super PACs in the second half of 2015 is a far cry from what they raised in the first six months of the year. Upon their formation in April, they touted taking in $31 million, and by the end of the first half of 2015, they reported raising more than $37 million. 

On Sunday, at least one of the Keep the Promise super PACs was drawing attention to its spending, not its fundraising. The four groups disclosed spending $8.5 million trying to elect Cruz during the last six months of 2015, most of it from the two most active members of the network: Keep the Promise I and Keep the Promise III.

Keep the Promise I, which reported unloading $3 million, said Sunday the number will be closer to more than $7.5 million once additional disclosures to the FEC in January are accounted for. The $4.3 million the group is expected to have spent in January is mostly on advertising.

"Patience, planning, and a strategic use of the funds entrusted to Keep the Promise I has allowed us to support Sen. Cruz's efforts and help defend him against specious attacks, especially as the race has intensified this past month," Kellyanne Conway, president of Keep the Promise I, said in a statement. "We're just getting started."

While the Keep the Promise super PACs only raised $1.2 million from July 1 through Dec. 31, they have already received a commitment for nearly as much this year. Republican megadonor Dick Uihlein has pledged $1 million to the groups, according to Keep the Promise I spokeswoman Kristina Hernandez. CNN first reported the commitment.

The Keep the Promise super PACs are the most well-funded outside groups backing Cruz, and the people involved in them have the strongest ties to the senator. Yet a less familiar entity, a super PAC known as Stand for Truth, is also raking in six-figure donations to support Cruz, according to the first disclosure of its finances to the FEC.

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Since its formation in November through December, Stand for Truth reported raising $2.5 million, spending $410,000 and having $2.1 million cash on hand. Its haul included a $1 million donation from the family of Adam Ross, a Dallas investment adviser who sits on the board of the Republican Jewish Coalition.

Also among the groups disclosing its finances Sunday to the FEC was Cruz's campaign, which has already announced raising more than $20 million in the fourth quarter of 2015 and having nearly $19 million on hand. The campaign's final figures show it took in $20.5 million, unloaded $15.6 million and has $18.7 million in the bank.

The campaign's cash-on-hand number is the largest in the GOP field. The campaign with the next closest amount of money in the bank is Rubio's, which has $10.4 million.

Notable donors to Cruz's campaign in the last three months of 2015 included Sheldon Adelson, the casino magnate whom GOP candidates are intensely courting. Adelson and his wife, Miriam, each gave the $2,700 maximum to Cruz's campaign.