Ted Cruz's presidential campaign said it raised more than $12.5 million in March, the biggest monthly fundraising total of the campaign.

Cruz has had success raising money from both a robust base of grass-roots supporters and a substantial network of rich backers - a formula that has continued as the Republican race has narrowed and wealthy donors who supported other candidates are turning to - or in some cases softening on - Cruz.

According to the campaign, it has now raised more than $78 million over the course of the campaign, which kicked off last March, from more than 450,000 donors. The average donation is $52 - lower than what it had been over the past few months.

"I am confident in this campaign’s ability to bring together all factions of the Republican Party," Cruz said in a statement.

The campaign did not release the amount of cash it currently has on hand. Cruz has increasingly been leaning on a super PAC supporting him, allowing him to keep resources as the nomination fight drags on. Cruz's campaign raised $66 million by the end of February, but entered March with only $8 million in the bank.