They’re giving him an extra 10 bucks on the credit, a handful of magic beans, and a solemn promise from Trump not to call him “Little Marco” for at least the next three months. Rubio votes yes. Put it in the books.

I shouldn’t make fun of him here, as he and Mike Lee are fighting a lonely fight for larger credits for poor families. Rubio’s an easy target because he’s earned his reputation for rolling over, distancing himself from the Gang of Eight bill, rubber-stamping Rex Tillerson, and shifting from NeverTrump in the primaries to endorsing Trump seemingly overnight. But he has, apparently, extracted a real concession this time. Last night he tweeted this:

Tax deal doubles #ChildTaxCredit from $1k to $2000.But for millions of #workingclass families only 55% of the $2K is available to them 2/2 — Marco Rubio (@marcorubio) December 15, 2017

Can only support bill if % of the 2K #ChildTaxCredit available to #workingclass parents is increased to % meaningfully higher than 55% 3/3 — Marco Rubio (@marcorubio) December 15, 2017

You’re entitled to offset your tax burden by $2,000 with the credit unless you owe nothing, in which case your “refund” from it is limited to $1,100. Rubio wanted more. According to GOP Rep. Kristi Noem, he’s going to get it:

The refundable part of the child-care tax credit has been increased to $1,400 per child, Rep. Kristi Noem (R., S.D.) said Friday after signing the final tax conference report… Ms. Noem said Mr. Rubio had not personally told her he would now support the bill, but she thought the boost would be enough to get him on board. “I believe that we’re in a good spot and we should be able to earn his support,” Ms. Noem said.

An extra 300 bucks in the refundable portion of the credit. How big of a win is that? Not much for most Americans, but if you’re poor it may be tantamount to a one percent pay raise. It’ll buy a crib or a thousand diapers, formula or baby clothes (or an Xbox, of course). Viewed as a percentage, an extra $300 is a 27 percent increase to an $1,100 refundable credit. It’s not nothing. It just *feels like* nothing because Rubio and Lee are trying to squeeze blood from a stone that bleeds pretty easily when it comes to lightening the burden of the upper class, as Rubio himself noted yesterday:

Tax negotiators didn’t have much trouble finding a way to lower the the top tax bracket and to start the corporate tax cut a year early. 1/2 — Marco Rubio (@marcorubio) December 14, 2017

Indeed. As I noted yesterday, Senate Republicans torpedoed the Rubio/Lee amendment to increase the child tax credit on grounds that they’d have to offset it by raising the new corporate tax rate above 20 percent, which they adamantly refused to do. Then they went to conference with the House and promptly raised the corporate rate to 21 percent to offset a cut in the income tax rate for the richest taxpayers, from 39.6 percent to 37 percent. The optics were atrocious — so bad, I think, that they might have thrown Rubio a bone here even if his vote wasn’t crucial to the bill’s passage. The “pro-family” party is used to Democrats sniping at them for not pushing more money to families, but when two conservative senators are making the same point, that’s a problem. Especially when they’re counting on the president’s blue-collar base, which will benefit from this play by Rubio, to save them next fall and in 2020.

Here’s Fox Business echoing the conventional wisdom that Rubio will soon climb aboard. Will he? Or will he demand a few hundred more for the refundable credit?