Democrat Beto O’Rourke trails Texas Republican Sen. Ted Cruz by single digits — 45-37 percent — according to new internal polling released by a Democratic group aimed at keeping corporate money out of politics.

End Citizens United’s poll, released Wednesday morning, comes weeks after Cruz’s campaign released its own internal numbers showing him leading O’Rourke 52-34 percent, with 13 percent undecided.

O’Rourke, a Democratic congressman from El Paso, has vowed not to accept money from corporate political action committees for his Senate bid. He was the first Senate challenger ECU endorsed for the 2018 midterms.

O’Rourke missed out on a different big liberal endorsement earlier this week, from the Texas AFL-CIO, after he skipped its convention.

Republicans control 51 of the Senate’s 100 seats this year. But the midterm Senate map, which traditionally favors the party out of power in the White House, provides few obvious pickup opportunities for Democrats.

Of the 34 seats that are up for re-election, Democrats must defend 24, plus two independents who caucus with the party. Ten seats are in states President Donald Trump won in 2016.

Republicans are defending eight seats, including Texas, which Trump carried by 9 percentage points in 2016.

Cruz isn’t considered a top target by either party, but Democrats are newly optimistic about their chances in some longshot races after a Democrat beat a scandal-plagued Republican in a special Alabama Senate election in December.

Cruz won approval from 38 percent and unfavorable review from 49 percent the ECU poll. Sixty one percent of respondents had never heard of O’Rourke. Twenty percent had a favorable opinion of him, while 19 percent viewed him unfavorably.

The poll was conducted by the Public Policy Polling, which works for Democratic interests, from January 17-18. It has a margin of error of plus or minus 3.6 percent. It surveyed 757 Texas voters, 73 percent on landline telephones and 27 percent online.

Sixty-three percent said they were more likely to support a candidate who has pledged to not accept money from corporate special interests. After telling respondents about O’Rourke’s pledge not to take PAC money, the poll showed him in a statistical tie with Cruz, 43-41 percent.

O’Rourke has an unusual relationship with outside money. He says he wants to raise the majority of his donations from inside the state and doesn’t want Super PACs spending on his behalf.

ECU is a political action committee that gets its money from small dollar donors, an average of $14 per donation. It raised $25 million last election cycle, and expects to raise $35 million for its 20 targeted 2018 races. The group says it has roughly 157,000 donors in Texas.

Cruz has also raised the majority of his large dollar re-election donations from Texans.

At the end of September, Cruz had about $5.7 million, to O’Rourke’s $2.9 million.