With key U.S. elections just over two weeks away, polls suggest the anticipated "blue wave" of Democratic voters might not be as powerful as it had seemed just a few months ago.

 

Democrats, while still favored overall, have been unable to build a decisive edge over Donald Trump's Republicans, meaning that the president might avoid the severe electoral slap-down the opposition party had hoped to inflict. 

 

Republicans have controlled Washington politics since the 2016 election. In addition to the White House, they hold a comfortable majority in the House of Representatives and a narrow but important edge in the Senate (51-to-49).

 

This could change on November 6, when the 435 seats in the House and one-third of those in the Senate (35) will be in play, along with numerous state and local positions.

 

After a multitude of marches, demonstrations and angry protests that followed Trump's surprise presidential victory, this will be the first chance for US voters angered by the real estate billionaire's policies and personal behavior to express themselves at the ballot box.

 

But it will also be the first chance for those thrilled by the nation's strong economy and full employment, as well as Trump's conservative court appointments, to show support for the president.

 

"The Democrats seem less and less likely to win the Senate," said David Lublin, a professor of government at American University in Washington.

 

If Republicans maintain control of the Senate, the chances that Trump might be impeached drop sharply -- barring any major new scandal -- because senators have the final word in these rare efforts to depose a president.

 

Trump could also continue pushing through his conservative judicial nominees, especially if there is another opening in the powerful Supreme Court, the final legal arbiter on the country's biggest and most socially sensitive questions.

 

"Democrats have lots of opportunities in the House, but not really the Senate," said Kyle Kondik, managing editor of a nonpartisan political newsletter at the University of Virginia Center for Politics.

 

"The House and the Senate always seemed likely to produce somewhat differing outcomes, which complicates a 'blue wave' narrative."

 

If Democrats do take control of the House they will be in a position to launch vigorous inquiries into the Trump administration's policies and behavior, and to block Republican-backed laws from passing, including a vote on the federal budget -- essentially giving them the leverage to paralyze Washington. 

 

- Urban vs. rural voters -

 

With an avalanche of Democratic candidates at all levels, including a historic number of women, and millions of dollars flowing into their coffers, the Democrats have aroused their base. For months this and expectations of a high voter turnout has led many to believe the party will at least retake the House.

 

This summer Democrats let themselves dream that their charismatic young senate candidate in Texas, Beto O'Rourke, might be able to knock Republican Ted Cruz off his senate seat in that large, deeply conservative state.

 

But polls have tightened in recent weeks, especially after the bitter fight in early October over conservative judge Brett Kavanaugh's confirmation to the U.S. Supreme Court.

 

Still, history is on the Democrats' side. The first midterm election in a president's term traditionally favors the party out of power. 

 

And Trump, for all the boisterous support he gets at his frequent rallies, is among the least popular modern presidents at this point in his time in office, polls show.

 

In the House, Democrats need to pick up 23 seats if they are to regain the majority, which analysts say is quite likely. The FiveThirtyEight political website, widely respected for its statistical analyses, gives the Democrats five chances in six to retake the House. 

 

But some 30 House races are still deemed too close to allow confident predictions.

 

The luck of the electoral calendar means Democrats face a much greater challenge in the Senate: they have to defend 26 of the 35 seats at stake, several of them in states that voted for Trump in 2016. 

 

FiveThirtyEight gives the Democrats only one chance in five of retaking the Senate. Republicans might even add to their lead there, pollsters say.

 

Even if Democrats are expected to pick up votes -- especially in the residential suburbs where political centrists oppose many of the White House's policies -- they still face a structural disadvantage.

 

The Democrats are "heavily concentrated in cities and urban areas ... (while) the Republicans are spread more evenly," said Lublin. And the tightest Senate races are taking place in more rural states.

 

- Reinvigorated Republicans - 

 

With the stakes high, Trump has been holding almost daily rallies in key states.

 

Before seemingly galvanized crowds, the president hammers away at key election themes: the threat of "radical Democrats," the influx of immigrants that will "infest our country," and the strength of the vibrant U.S. economy.

 

So even if Trump's name is not on ballots on November 6, there is no question his shadow will loom over the vote.

 

"Come Election Day, Americans will remember Kavanaugh," Trump bellowed at a recent rally in Montana, pointing to signs that Republican voters were mobilized by the judge's rocky confirmation process that included allegations of sexual misconduct.

 

It's unclear if this "Kavanaugh effect" will last until the election -- and whether it will be enough to overcome the Democratic voters outraged that the allegations against the judge were dismissed with little investigation.