A top Democratic group issued a warning to party leaders nine months out from the midterm elections: It's still the economy, stupid.

The prominent super PAC Priorities USA released a polling memo Tuesday showing that as attention has been centered on White House scandals and immigration the past few weeks, Democrats have been losing ground on taxes and the economy.

The findings deliver welcome news for Republicans, who have been working on improving public perception of their originally unpopular tax bill and also banking on an improved economy in 2018. The Priorities' survey shows upticks in President Trump's job approval rating, along with increased approval on key GOP policy items including health care, taxes and the economy.

"There’s no question that Trump benefits when a critique of his tax and health care policies is not front and center – especially when voters are hearing Trump’s side of the story on the economy," the memo reads. "In the last few weeks, Democrats turned their attention to other issues while Trump has continued to promote his economic policies, and Trump’s numbers have incrementally improved as a result."

The memo comes as Democrats have sought to harness the anti-Trump fervor among their base while crafting a longer-term message to regain voters it lost in the last presidential election. While Trump has energized the opposition more effectively than Democratic leaders could, the party's path to majorities in the House and Senate includes districts and states the president won. And while some fundamentals still favor Democrats ahead of the midterms, the memo warns that the party is losing focus, and could give up those advantages by focusing too much on Trump and not enough on its own message.

"Even while waging other important fights, Democrats must continue to focus on economic issues like taxes and health care and not allow themselves to be sidetracked and distracted by Trump’s latest tweets," the memo reads.

The Priorities survey, conducted by the Garin-Hart-Yang Research Group and the Global Strategy Group during the first week of February, found that Trump's job approval among presidential-year voters ticked up four percentage points since November. The survey shows 44 percent of voters approve while 53 percent disapprove, compared to 40 percent vs. 54 percent three months earlier. (The RealClearPolitics polling average has the president at 41.4 percent/53.9 percent.)

The poll tracked similar improvements on policy areas. Among those surveyed, 34 percent registered a favorable view of Trump's health care policies, compared to 46 percent unfavorable (up from 23 percent/53 percent). On taxes, 46 percent view the policies favorably while 42 percent view it unfavorably (up from 32 percent/48 percent). And on the economy, the numbers are 46 percent favorable/39 percent unfavorable (up from 38 percent/43 percent).

The memo argues that majorities of voters share Democrats' concerns that the new tax bill and Trump's economic policies will enrich the wealthy and big corporations while hurting the middle class, but it notes that the party's related messaging isn't penetrating. "When voters have heard messages from both Democrats and Republicans on the tax bill, Democrats have won. Unfortunately, that debate has been relatively one-sided recently and voters have not heard nearly as much from Democrats," reads the memo.

Republican groups, meanwhile, have shown they are prepared to spend what it takes to improve public support for the tax law, which the GOP touts as a key accomplishment. The Koch brothers, for example, announced last month they plan to spend $20 million promoting the tax overhaul as part of a $400 million investment in the midterm campaigns.

Even those bullish on Democrats’ chances are taking note. "Ultimately, as we head into the 2018 midterms, I’m confident that a blue wave is building. But I’m left wondering: Is our surfboard big enough?" veteran party operative Jesse Ferguson wrote in a recent op-ed.

The Priorities survey indeed finds plenty of positive data for Democrats. By a 51 percent-39 percent margin, voters said they prefer to see more Democrats elected to Congress in 2018 as a check on Trump, rather than more Republicans to help him pass his policies and programs. It also cited a significant expected-participation level: 69 percent of presidential voters ranked their enthusiasm about voting in the midterms between a seven and a 10 (on a zero to 10 scale).

The pollsters also showed Democrats have a four-point advantage in the generic ballot. However, public polling has shown recent dips in that number. A month ago, the RCP average showed Democrats with an 11-point edge. Now, it stands just below seven points.

The Priorities memo comes as lawmakers are starting debate over immigration policy. Earlier this year, Democrats suffered the blame for shutting down the government, insisting a vote on immigration policy be attached to a funding bill. The move was in response to demands from their activist base, but the party gained little from the effort. On the second go-around last week, Democrats provided enough votes for passage of a budget, even though House party leaders stood against it.

The polling memo released Tuesday urged Democrats to keep their eyes on the ball. A tweet from Priorities USA Chairman Guy Cecil underscore this point:

The immigration fight is critical and should be fought at every level. It is also important that when we engage these fights we don't cede ground on other critical issues/messages. https://t.co/X01MS5VrD8 — Guy Cecil (@guycecil) February 13, 2018

"Democrats continue to hold an advantage over Republicans heading into the midterms but must reassert control over the economic narrative if they are going to maximize electoral success in House, Senate and governors’ races this fall," the document reads.