Republicans’ final, 48-hour push to win the six seats they need to control the Senate began Sunday with good news in three southern states central to the GOP’s strategy.

New NBC News/Marist polls released on “Meet the Press” show Republicans leading in Georgia, Kentucky and Louisiana — or poised to prevail in subsequent runoff elections. And in the pivotal Iowa Senate race, a Des Moines Register poll posted online Saturday night and blared across the front page in Sunday’s editions showed Republican state Sen. Joni Ernst with a 7-point lead over Democratic Rep. Bruce Braley.

Prominent Democratic strategists are growing increasingly nervous that the national political environment is not only bad for their side but is moving in the wrong direction in the final days before the election, a trend that could not only cost them control of the Senate but also visit double-digit House losses on the party.

“The environment has settled and it’s bad,” said one senior Democratic party operative closely monitoring the party’s prospects this fall.  The source added that Democratic candidates’ numbers among independents and seniors — two critically important voting blocs — have begun to erode; “they are just not as friendly  to us as they once were,” the source explained…

“This off-year election has become almost entirely a referendum on the president,” said one Democratic consultant involved in a number of closely-fought congressional races. “It’s not just anger at [the Affordable Care Act].  He has become, in my opinion wrongly, the symbol of dysfunction in Washington.  That has led to a demoralized Democratic base, energized Republicans and those in the middle have an easy way of venting their frustration, and that is to punish the president’s party.”…

Asked for a single word to describe why this election was looking increasingly bleak for Democrats, one consultant offered “Obama.”

“It’s a grim environment,” said Representative Steve Israel of New York, the chairman of the Democratic Congressional Campaign Committee. Mr. Israel was spending the weekend pleading with his caucus to contribute to imperiled colleagues to minimize losses. Trying to soften the blow, he noted that losses were expected: The party in control of the White House has lost an average of 29 seats in midterm elections in the last century…

Senate Republicans are confident. A senior party official called Senator Mitch McConnell of Kentucky, the minority leader, on Saturday at his Louisville home and, after running through voting projections, told Mr. McConnell that he would be the next majority leader. Mr. McConnell’s initial reaction was only a long pause…

Democrats were increasingly worried about Senator Mark Pryor of Arkansas and Senator Mark Udall of Colorado. If they lose and Republicans win an open seat in Iowa or defeat Senator Mark Begich of Alaska, that will be enough for the Republicans to capture the majority, provided they hold their other seats and take, as they are expected to do, seats held by Democrats in Montana, South Dakota and West Virginia…

“It is hard to say the situation has improved in the last couple of days,” acknowledged Mark Mellman, a Democratic pollster.

Put another way, Democrats face a worse version of the same problem that burdened the GOP in 2006, when Bush’s approval ratings fell to around 45 percent in those key tipping-point states.

Republicans say they’ve done more this election cycle than in previous ones to talk about local issues and prosecute a broader case against Democratic candidates around the country. But they’ve also plainly sought to maximize the impact of Obama’s unpopularity on the election…

So while the Republican brand is not particularly well-liked nationwide, the party’s 2014 candidates don’t have the personal baggage that helped offset the drag of Obama’s unpopularity in the past.

That Democratic candidates have managed to remain competitive this year under these circumstances is impressive. But it might not be enough, especially for contenders like Iowa’s Braley, whose many problems (seen by at least one observer as fatal) will be eclipsed by the president’s negatives as the determinative factor on Tuesday night.

You know, the Republicans will do well in the red states. They’re probably going to do well in Arkansas, places like that, West Virginia, obviously, probably Louisiana, but if the victory — winning over your own people is good. It’s not a huge victory.

So they could do that and still even win the Senate, but if they can get in these purple states, then they’re really showing — they’re breaking out of their pattern, and their pattern has been, especially over the last four years, is they’re toxic. People, even some traditional Republicans, are unhappy with the Republican Party.

But has the party detoxified themselves? Have they returned from sort of a Tea Party, which generates intensity, but scares a lot of people? Are they now seen again as sort of a business party that maybe will get the economy going? And if they start winning some of those purple states, the North Carolinas of the world, or even if Scott Walker wins in Wisconsin in the governor’s race there, then you begin to think, OK, they have improved their image with some of the swing voters.

Whipsawed by events and facing another midterm electoral defeat, President Obama has directed his team to forge a policy agenda to regain momentum for his final two years in office even as some advisers urge that he rethink the way he governs.

Without waiting for results from elections on Tuesday that few in the White House expect to go well for Mr. Obama, top aides have met for weeks to plot the final quarter of his presidency. Anticipating a less friendly Congress, they are mapping possible compromises with Republicans to expand trade, overhaul taxes and build roads and bridges…

Among advisers inside and outside the White House, there is a growing sense that Mr. Obama has closed himself off within a shrinking circle of aides. Some advisers who had been influential said they were no longer consulted as much. They worry that Denis McDonough, the White House chief of staff, has taken on too much himself…

Joel P. Johnson, who was Bill Clinton’s counselor late in his presidency, said Mr. Obama should test Republican intentions soon after the new Congress takes office. “Make it clear there is a negotiating table awaiting, and don’t shut down the possibility that there could be a dialogue that results in something that’s progress,” he said.

You may recall that Mitt Romney built his entire 2012 campaign strategy around the assumption that a terrible economy would suffice to deny Barack Obama a second term. Yet throughout 2012, with the unemployment rate still up around 8 percent, Obama’s approval numbers stayed high enough (the mid-to-upper 40s) to ultimately win. Whereas today the unemployment rate has fallen to 6 percent, a number Team Obama would have traded David Axelrod’s right kidney for two years ago, but the White House hasn’t benefited: The public’s confidence is gone, and it doesn’t seem to be coming back…

One of the interesting features of the 2012 campaign was that as much as the economy made Obama’s sales pitch challenging, he had an edge that Democratic politicians often lack: The public trusted him on foreign policy. But that trust began to erode with the Edward Snowden affair, it eroded further during our non-attack on Bashar al-Assad last fall, and recent events in Ukraine and Iraq have essentially made Obama’s position irrecoverable: His approval rating on foreign policy is around 35 percent in most recent polling.

But this harsh judgment probably isn’t explicitly ideological: The public isn’t necessarily turning neoconservative or pining for the days of Bush. Instead, it mostly reflects a results-based verdict on what seems like poor execution, in which the White House’s slow response to ISIS is of a piece with the Obamacare rollout and the V.A. scandal and various other second-term asleep-at-the-tiller moments. It’s a problem of leadership that reflects badly on liberalism but doesn’t necessarily vindicate conservatism…

In many ways, Republicans have enjoyed in 2014 the kind of landscape they expected in 2012: a landscape in which nobody save Democratic partisans particularly supports President Obama anymore. What we’re about to find out is whether, amid that disillusionment, just being the not-Obama party is enough.

Even if the Republicans win [Iowa, North Carolina, Colorado and Georgia], which would all but ensure Senate control, it will probably be mostly because of low midterm turnout among Democratic-leaning young and nonwhite voters. The implication would be that Republican Senate candidates did not win many voters who supported President Obama in 2012. And it would suggest that Republicans have made little progress in attracting voters they would need to take back the White House.

If there were a time when the Republicans ought to be making inroads into the Obama coalition, this should be it. The economy remains mediocre in many respects; there is turmoil in much of the world; and the American public is decidedly downbeat about the state of the country under Mr. Obama. His approval ratings have sagged into the low 40s. A significant proportion of Democratic-leaning voters say they disapprove of his performance.

Historically, presidential ratings like these have permitted the party that does not hold the White House to make substantial gains. This year, however, Democratic Senate candidates in the battleground states have largely reassembled the coalition that supported Mr. Obama two years ago. Democratic candidates would probably win Colorado, North Carolina, Iowa and Georgia — along with control of the Senate — if those who vote were as young, diverse and Democratic as they were in 2012 or will be in 2016.