Polls show Democrats with an advantage in the House. They still might not take Congress.

Polls show good, but not great, signs for Democrats.

Democrats have a seven-point advantage over Republicans in voter preferences for the House of Representatives heading into Tuesday’s midterm elections, according to new polls. It’s not clear whether that will be enough to allow them to take back control of the lower house of Congress.

A Washington Post-ABC News poll released on Sunday found that 50 percent of registered voters want Democrats to take the House while 43 percent prefer Republicans. That’s tightened from previous iterations of the same poll: In August, registered voters preferred Democrats to Republicans 52 percent to 38 percent, and in October, the split was 53 percent to 42 percent.

Among likely voters, Democrats have an edge as well, with 51 percent saying they prefer Democrats and 44 percent Republicans. As the Post notes, the seven-point advantage could give Democrats the margin they need to take the House majority.

A separate NBC News/Wall Street Journal poll also released on Sunday shows Democrats with the same edge over Republicans in House races, with 50 percent of likely voters saying they prefer Democratic-controlled Congress and 43 percent saying they’d rather have Republicans in charge. Among registered voters, Democrats have a six-point edge.

But there are some positive signs for Republicans as well, particularly when it comes to the economy and border security.

According to the Washington Post-ABC News poll, the GOP has a nine-point edge over Democrats when it comes to who registered voters trust to handle the economy. Moreover, people appear quite optimistic — 65 percent of Americans say the economy is good or excellent, the best marks since January 2001, according to the Post. Among registered voters, 71 percent say the economy is good or excellent. And people feel that on an individual level too, with 28 percent of respondents saying they’re better off than when President Donald Trump became president and 58 percent saying they’re the same. Just 13 percent said they’re not doing as well.

Trump has made much of his closing argument about border security, stoking fears about immigrants and a migrant caravan hundreds of miles away from the border. He’s making a show of sending thousands of troops to the border.

The message might be getting through, because 39 percent of registered voters say they trust Democrats on handling border security compared to 49 percent who trust Republicans. The share of Republicans who say immigration is “one of the most important issues” they’re voting on increased from 14 percent to 21 percent since the last iteration of the Washington Post-ABC News poll.

While the GOP is ahead on the border, voters say they trust Democrats more on immigration by a five-point margin. And Democrats lead Republicans significantly on who registered voters trust on health care, 50 percent to 34 percent.

Trump’s approval rating is still low — 44 percent of voters say they approve of the job he’s doing, and 52 percent disapprove — but it’s the best margin the Washington Post-ABC News poll has found during his presidency. In the NBC News/WSJ poll, Trump’s approval rating was also relatively unchanged from previous polls, with 46 percent of likely voters saying he’s doing a good job and 52 percent saying he’s not.

That could hurt his party’s chances: As the Post notes, Trump has made the election more about himself than most presidents, and his low approval rating could drag Republicans down, despite positive perceptions of the economy.

Who takes control of the House will ultimately come down to tight district-by-district contests, and Democrats need to gain 23 seats in total. These issues will each play differently in individual contests, and the seven-point across-the-board advantage might not be enough for Democrats to get the seats they need. With the level of gerrymandering of congressional districts, Democrats might need a wider margin nationally to win Congress — a report from the Brennan Center for Justice earlier this year found that Democrats would need to win the popular vote by 11 points to take back the House.