US midterm elections test Trump's grip on power as voters fret over war, rising costs; what's at stake?

Voting began in several US states on Tuesday in midterm elections that could reshape the balance of power in Congress and deliver a major political verdict on President Donald Trump.

Trump returned to the White House promising to keep the United States out of foreign wars.

But barely a year into his second term, he plunged the country into a conflict in West Asia.

His convoluted rationale: The United States acted to pre-empt retaliation against the planned Israeli strike.

Now, with his approval ratings hovering near their lowest levels, Trump faces one of the biggest tests of his presidency as voters weigh the costs of the conflict, rising fuel prices and concerns about affordability.

The elections will determine control of Congress, as all 435 seats in the House of Representatives and 35 of the Senate's 100 seats are up for grabs.

Democrats need to flip at least three House seats and four Senate seats to secure majorities in both chambers.

Trump has repeatedly urged supporters to treat the elections as a personal contest, telling them to "pretend I'm on the ballot."

But Republican candidates appear increasingly reluctant to associate themselves with the president in their campaign advertising.

An analysis by Axios found that Trump featured in 66% of House Republican primary advertisements but in just 3% of their general election ads.

In Senate races, the share of Republican advertisements mentioning him fell from 77% to 22%.

His presence in Republican gubernatorial campaign ads also declined by 34 percentage points.

The shift comes as voters overwhelmingly identify the cost of living as their biggest concern and express dissatisfaction with Trump's handling of the economy. His sweeping tariff policies and the decision to attack Iran in February have added to domestic cost pressures.

Trump has sought to rally his political base through more than two dozen campaign appearances since the beginning of October, most of them in states he comfortably won in the 2024 presidential election.

Republicans, meanwhile, have sought to portray Democratic candidates as radical and out of touch with American values.

"The Democrat Party has nominated the most extreme and dangerous slate of candidates in American history," Trump said on Monday during a speech in Washington.

But opinion polls suggest that affordability, rather than ideological battles, is dominating voters' concerns, leaving Republicans vulnerable in several closely contested races.

What's at stake?

A Democratic takeover of either chamber would substantially complicate the remainder of Trump's presidency.

Control of the House would give Democrats the power to launch investigations into his administration and business dealings.

A Democratic-controlled Senate could also block presidential appointments, including nominations to the Supreme Court if vacancies arise.

A Republican defeat would further weaken Trump's political standing at home and abroad, particularly after he has repeatedly framed the midterms as a referendum on his leadership.

Democrats, however, face a difficult electoral map despite putting Republicans on the defensive in several traditionally Republican strongholds.

The party must defend all its existing seats while making gains in states that backed Trump by double-digit margins in 2024.

Among the targets are Alaska, Iowa, Kansas, Nebraska, Ohio, South Carolina and Texas.

Opinion polls show Democrats either narrowly leading or within striking distance in several of these states, but the party has little room for error.

The election will also offer an early indication of the political dynamics ahead of the 2028 presidential race, as potential successors to Trump begin positioning themselves within both parties.

A Republican victory, meanwhile, would strengthen Trump's hand considerably.

It would reinforce his influence over the party and provide fresh momentum for his legislative agenda.