The Christmas season was not a very jolly one for Republicans. Donald Trump's approval numbers were near historic lows while the so-called generic ballot measuring the relative strength of both parties saw the Democrats with a double digit lead.

But then came tax reform, which has proven to be even more popular than Republicans hoped. A Trump facedown with Democrats ended in the opposition's surrender on the funding bill, and a state of the union speech by Trump that received overwhelming positive response.

On top of all that, the economy is booming, interest rates are low, consumer confidence is high, and the economic outlook for the year is for more of the same.

The result of all this is that the president's approval numbers have shot up and the gap between the GOP and Democrats on the generic ballot has narrowed considerably.

The Hill:

A Monmouth University Poll released Wednesday showed that Trump’s approval rating had jumped 10 points compared to last month, while the Democratic advantage on the generic ballot had shrunk to 2 percentage points.

A nationwide Monmouth survey in December showed Democrats with a 15-point advantage on the generic ballot.

The generic ballot question, which asks respondents if they would be more likely to vote for a Democratic or Republican candidate in their own district, is considered an indicator of future wave elections. 

A Reuters/Ipsos poll released Wednesday showed that Trump’s approval rating has ticked up in the past week. 

Another Reuters/Ipsos poll shows voters think Republicans have a better plan for jobs and employment than Democrats, by a margin of 37.6 percent to 27.8 percent.

“The numbers for or against Republicans in different states have moved dramatically favorable, where two months ago there was a much lower rating,” said Sen. James Lankford (R-Okla.). “There were about four or five polls they listed out.” 

The swing in the polling numbers has been matched by a swing in sentiment. 

Adding to the growing confidence of Republicans is a closer look at those generic ballot polls. Most of the Democratic advantage lies in running up huge margins in districts they already control.

ABC News:

The wide Democratic advantage in congressional vote preference comes entirely in districts the party already holds, raising questions about the extent of its possible gains in November. Yet the closeness of the contests in GOP-held districts underscores this year’s Republican vulnerability.

Democrats lead by 14 points among likely voters in the latest ABC News/Washington Post poll, a result reported previously. But that reflects a vast 38-point Democratic lead in districts already held by Democratic members of Congress. In districts the Republican Partyholds, by contrast, it’s a tight 45-51 percent Democratic vs. Republican contest.

The Democrats' lead in their districts, 64-26 percent, marks the extent of potential Democratic overvoting in areas where they’re already in control – which partly reflects a Democratic concentration in urban areas, and possibly also gerrymandering of district lines.

In part, the difference in the margin of support between Democratic and GOP districts lies in the relative enthusiasm Democrats have for voting in mid terms. It should be a warning to Republicans that their margin for error from now until November is small and that every effort should be expended getting their voters to the polls.

But at the very least, these numbers should put a crimp in the Democrat's breezy confidence that the House and perhaps the Senate would simply fall into their laps after mid terms. They've got to know now they've got a fight on their hands and can take nothing for granted here on out.